My wife won't fuck me but her sister will

I've always had a bit of a crush on my sister-in-law. She's lively, funny, naughty and a tad crazy. Could I live with her? Hell no. But do I wonder what she tastes of, whether she has a hairy pussy or not? Of course. I never ever thought that I would ever find out. It was just fantasy. She always asks me to do the odd job for her and Suzie encourages me to help her when I can. I never even got a hint that she wanted me, not once! I was speechless. Quite literally speechless when she presented her hairy pussy to me on the staircase after she must have removed her knickers in the bathroom. How could I say no? Of course I could not.