I promise you that it's true. It all started the day that her sister asked if she could borrow $20. I said I would, but it would cost her. I told her that she had to show me her tits and she did. A couple days later she asked if she could borrow another $20 and told me that she knew it would cost her. This time I licked her nipples. The next time it moved to me jerking off as I played with her tits and came on her. The last time it happened when I was dating her sister, I came in her mouth. Then the ex and I broke up, and I didn't talk to any of them for about 2 years, until I ran into her sister. We swapped numbers and she called about a week later. We ended up fucking twice since then. Since then I was in an instant message chat with the third of 4 sisters and it got dirty. Next thing I knew she was talking all filthy and got me off. I still haven't fucked her, and trust me when I say this...I've tried, but havent quit.
As far as the question about did my ex know....I'm not sure. I really dont think so. I was always trying to work a 3-way, and almost had it, but it didn't happen. We were always very flirty, so i'm sure it didnt seem overly awkward. I actually sucked my ex's, sisters tits and shot on her as she was laying on my living room floor and my ex was sleeping in the bedroom about 20' away.