I have to say that this to me is a very touch subject. I did have a boyfriend who did cheat on me but I did not know that it was someone that I knew. I was only dating the guy for little about two months. For some reason one of my friends told me and I asked him but he just deni the hole thing. In my situation I just put up a big wall and just push him far away from me. In the end I just broke up with him. I later went up and asked the person that he cheated on me with and she told me that she was really sorry and that it really shouldn't of happend in the first place. I just told her that at the time I was pissed off but now I just put it behind me and we wound up being friends. In my opinion I really don't think that someone should come between friendship but........ if that does happend you just need to believe that there is a reason why, and try not to think about it as much.