Asked by my sister-in-law

I was a bit shocked when straight out by my sister-in-law (SIL) for sex. She is 53 two years older than me and 4 years younger than my brother her husband. My brother has become overweight and prefers playing golf to fucking his wife. I'm widowed due a car accident and wasn't in any relationship at the time. I keep fit by exercise and live next door to my brother and SIL. I'm always visiting for one reason or another mostly fixing things as my brother can't be bothered to do anything outside of his job or playing golf. So, as I was over fixing a leaky tap, I was asked to fuck by my SIL. Once the shock had passed, I agreed and that was the start of my new sex life. My SIL loves sex and is always willing and best thing is us being seen together isn't unusual as we're regularly together with or without my brother.