Old Family Friend

I was 20 when this all started, not living at home I was out on my own. Almost qualified as a mechanic, I'd bought a rundown 4brm 2bath house and was doing it up. Got at a bargain price with a bank loan, I was finished the everything except the second bathroom. It didn't seem important as I was living alone at the time. Bedrooms were easier to finish no plumbing to replace so it was mainly fixing window, door, clean walls and paint. As I'd the house rewired after the roof was replaced. We'd a terrible storm which damaged a lot of home in the town, an old friend of the family. We called auntie (53) widowed home was damaged roof partly removed by high winds. Unable to stay in her house until it was repaired, her belongings moved into storage till her home was fixed. A lot of damage done by the storm and there was a waiting list for repairs to be done. My parents already had my mother's parents living with them so had no room for auntie. I was the obvious next choice I'd 3 spare bedrooms. Aunties own family were interstate with their own families. I was happy to have her stay with me, it was supposed to be about 8 or 9weeks. It turned out to be 7. Auntie is the hugging type with family and close friends. She done the cooking and even done my washing, about a week after she had moved in. I was showering and started playing with myself but hadn't actually started masturbating myself at the time. Just soaping my cock, it was responding but still hanging down but starting to get bigger. When auntie came in and goy an eye full as they say, clear glass no fogging of the glass she saw me totally naked. To my surprise she didn't leave instead she asked did I want her to wash my back. Thinking she was joking I replied Oh yeah, I'll love that. She then stripped naked and joined me in the shower, I was somewhat surprised at first. But it soon passed, she sponged my back and then started on my front, my cock was still hanging semi hard. But as she sponged it went rock hard and pointed straight at her. Seeing it she just started stroking it and then told me to fuck her. A willing woman is something I haven't found many of at the time. So, I fucked her, and she slept with that night and twice a week thereafter. A mutual benefit relationship she called it. With her house repaired, she moved back home, but we've continued our mutual benefit relationship. I stay over her place for a night, or she stays over at mine for a night. I've since gotten a girlfriend who works at the hospital reception and works shifts, but she lives with me. My sexual relationship with auntie is still going and we fuck when my girlfriend is working nights or weekends. It's a perfect relationship, can be seen together as nobody would think we're lovers.