My Stepsister caught me. (Edited)

I was in my last year of college in the mid-eighties when something happened that for me turned out to be the best summer of my life.
I have a very close family, some say too close since my parents divorced a few years ago.
So it's just me, my older stepsister, and my constantly depressed mother.
My older stepsister is from my father’s first marriage; she stayed with me and Mum as her father was a bit of a piss head, constantly drunk, and wasn't worth bothering with.
She is in her twenties, works all day at some shop, then comes home usually in a mood but can be a bit of an arse sometimes.
I normally get on with her, but she's not the nicest-looking stepsister, but I guess baggers can't be choosers.
Mum, on the other hand, hasn't really got over her divorce; he cheated on her multiple times, and she hadn't taken it well since he left us to go with his affair.
I do my best to pacify her and do what I can to help alleviate her depression.
Which turned out to be more of a bonus for me, but that I will elaborate on as you read on.
How this summer turned out to be the best I've ever had started one afternoon when I thought I was alone in the house.
As my studies are so important to me, I spent a lot of time in my room; this doesn't give me much chance to date any of the very attractive girls in my neighbourhood.
To compensate, I mostly every day jerked off to give myself some light relief from the constant studying.
The thing was, I needed some sort of stimulation, which I found in my mum’s panties. She doesn't date, but as she's single, I know she spends a lot of time pleasuring herself with the array of toys she uses to give herself, like me, some light relief.
Most mornings, after one of her sessions, I would find a fresh pair of Mum’s very aromatic pants in the wash basket, some rather skimpy ones but mostly the black ones women seem to wear when they aren't getting any cock.
With those, I can have some amazing hand jobs and splatter a good liberal amount of my cum over.
This went on for quite a while until I was in the middle of one very intense session. I was just about to explode when I heard someone scream,
“Are those Mum’s pants, you jerking your dick over her pants?”
Looking up, I found my twenty-two-year-old stepsister standing at my door with her phone in her hand, filming me pumping the hell out of my cock with Mum’s pants wrapped around my bloody throbbing eight-inch shaft.
“Don’t you ever knock,” I screamed.
“She's going to kill you when she finds out. I'm going to show her what you’re doing with her pants, she's going to kill you,” she said.
Standing up, I lunged for her phone. “Argh, no chance I'm keeping this.”
“Look, just delete that vid, will you?” I said.
Trying desperately to get her to delete the video, she just laughed at me.
“ Why should I? I doubt Mum’s going to be happy when I show her this.”
“You can’t, okay, Mum’s depressed enough without her knowing I cum on her pants,” I said.
“So what, it's disgusting, you could ruin them doing that.”
“Yeah, well I bet yours are as bad after what you get up to with those mega-size dildos you use,” I said.
That's when she saw my cock. It started to go limp but just as she looked at me it just had a mind of its own, it returned to bring hard and even as I tried to cover it up she noticed how big I was.
“Bloody hell, that's huge, I know I'm your stepsister but Jesus Christ what I could do with that thing,” she said.
“Excuse me, what?” I asked.
“That bloody cock, I know you're my stepbrother by god you could sort me out with that thing,” she said.
“You're telling me that you would rat on me to Mum about her pants then in the same breath want my cock.” I said.
“ ok look, I won't show Mum this video if you let me use your cock, not had one that size and it's been a while since I had a good fuck,” she said.
“You want me to fuck you to stop Mum seeing the video, what's to say I do, you could still show her anyway.”
“ I won’t if you have sex with me, why would I ruin any chance of sex if I would show Mum what you do with her pants,”. She said.
What was going through my mind was the fact my step-sister wants me to fuck her, which I don't mind doing, but what she didn't realise was Mum already knew I used her pants to jerk off over.
About a month ago, Mum was having one of her episodes when she caught me jerking off over my stepsister's panties.
I was going like hell on my cock, but I had my sister's panties when I heard a voice saying, “ You do realise, son, your sister’s going to kill you if she knew what you do with her favourite panties.”
Mum was standing with a wash basket in her hands. I jumped up saying,
“Oh Christ, sorry, Mum, please don't tell her, will you?”
“Well, I should, but I won’t, but please just be careful. If she found out, she would make all our lives hell. You know what she's like.”
“ I won’t, I promise,” I said.
“Look, if you like pulling that cock of yours instead of you using your sister's pants, use mine. I will leave you a fresh pair in the wash most mornings. Just make sure you put them back for me to wash.”
I couldn't believe what she’d just offered me.
“You sure, Mum?” I said.
“Yes, it's been a while since I've had a cum in my panties, so as it’s yours, I don't mind,” she said.
From then on, Mum was true to her word, a fresh pair of perfumed pants readily for me to cum over.
Over the next week, my Mum’s panties got so much of my cum splattered over them that one morning I was in the kitchen when she came in saying,
“Christ, son, just picked my pants out of the basket, you got anything left in those balls of yours,” she said.
“Sorry, Mum, couldn't help it.”
“No, don't apologise. It’s a shame you have so much, it seems a waste, don't you think?” “ I guess, but what else can I do? I'm studying most of the time I'm not dating, so it's the next best thing,” I said.
“Well, there is another option, but that I'm not sure you could handle.”
“Oh, I can handle anything, trust me,” I said.
“ ok how about this, you like to jerk of regular right,” “ yeah,”
“ I use my vibratir as much as you jerk on your cock,”
“ ok” I said.
“Well I've not had sex in nearly a year, you shoot cum, I hate vibrators, so why not put what I've got and what you've got together,” she said.
“ what as in me having sex with you,”
“ why not, I know I know I'm your mother but to hell with that I need sex, you have a cock and I can't go much longer without a good fucking.” she said.
Now my mother isn't in too bad a shape, smallish backside, nice pair of tits and I'm guessing after going so long without a tight hairy pussys.
“ ok if I agree how's this going to work then,” I asked.
“ simple if either of us is horny, we have sex,”
“ what full naked sex or just a quicky, drop our pants and just go for it sex,” I asked.
“ for now let’s just try the quicky route, be we progress to full naked sex,”
I couldn’t believe what I was hearing, mom wanted my cock and to be honest I wanted her hairy pussy.
“What do you reckon?” she asked.
With no hesitation and the thought of fucking Mom’s very hot body,
“ ok if you’re up for it, Mom.”
“Do not say a word, if this gets out, we are both screwed big time.”
“ ok mom”
“We will keep it simple, no foreplay, just fucking, that's it for now,”. She said.
“Works for me, Mom.”
We waited until my sister left the house. Mom met me in the kitchen, saying, “ You hard?” “Never stopped.”
“ ok come with me.”
Leading me to her bedroom, she closed the door behind us.
“Right, get your cock out and just give me a quick fuck ok”
Instantly, I dropped my pants as Mom whipped off her panties. Turning round, she knelt over her bed.
“Right, I'm assuming that you know what to do.”
“ fucking to right I do,” I said.
Moving in between her legs, I held my now hard cock and guided it towards my mom's hairy waiting pussy.
“Just slip it in and make me cum,” she said.
I couldn't believe what I was doing. I was fucking my mom's pussy. It just didn't seem real.
As she was very wet already, I slid straight in. Holding her hips, I pulled myself right in. Mom gave out a loud groan, saying,
“Jesus Christ, that feels tight. I forgot what it felt like.”
“ god Mom, you're so wet it feels fucking amazing.”
“ ok well, fuck the arse of me then before your sister gets back.”
With that, I went for it. I banged the hell out of my mom's very wet, hot pussy, her lips wrapping around my cock as I slid in and out.
After some heavy thrusting, it wasn't long before she screamed, saying,
“God, son, here it comes. I'm fucking going to cum hard.”
I then let rip. I went at it like a train and slammed my cock fully into her as she exploded on my fully inserted cock. We both came together. Her orgasm rippled through her body as my cum filled her hole.
Holding myself in for a while, she then fell forward, pulling off my glistening cock.
Both our juices poured from her well-satisfied pussy.
“How was that, quick enough for you,” I asked.
“Too fucking right it was. You can do that again, I can tell you.”
Looking at my stepsister she looked at me,” well you up for sex with me or not, I can still show mom this video you know,” she said.
“ ok look fine, if you want sex you can have sex, but get rid ipof that video and you can have as much bloody sex as you want,” I said.
“ ok deal, but this stays between me and you ok, if mom finds out gid knows what she will say.”. She said.
“ thinking back to how me and mom started it felt like ground hog day, everything replying over again, mom wants my cock, my stepsister also wants my cock and neither of them know I'm fucking them both.
Again I needed to know what she wanted so again I asked the same thing,” how's this going to work then, you want just quickie, drop pants and just go for it, or full naked sex with all the extras,” I asked.
Just quickies fir now, as and when, will try that first, see how that goes,” “ ok so when,” I asked.
“ well as your already naked, semi hard, we are alone why not now,” “ ok get your pants off and lay on the bed,” I said.
Closing the door behind her she lifted her skirt and promptly whipped off her large wet pants.
Lying down on the bed she interacted me to just slip it inside her and just fuck her for now.
Watching her get comfy she laid back and just like that opened her chubby legs.
Her hairy pussy just fell open and the sight of my stepsisters pussy wide open got me harder than ever.
Moving in between her legs I guided my cock straight towards her open pussy, that first push inside he made her groan but as she was very wet already I slid right in as deep as I could.
She grunted and groaned as I started to fuck her, each hard stroke giving her what she wanted.
It didn’t take us long as we both orgasmed at the same time.
My hot cum filled her pussy as I throbbed inside her as my own orgasm started to subside.
I had fucked my stepsister as she sat up saying,” right now that I liked, if your up for more then keep that cock ready ok,”. She said.
Sliding out of her she stood up and wiping herself on my towel promtly left my bedroom.
I now had moms pussy on call, my stepsisters pussy as well and they didn’t know I was fucking them both.
Every other day it was either moms pussy or my stepsisters what more could I ever ask for.
That summer turned out for me the best ever.