Hey champ, my buddies X did the same thing. The problem is, he went and talked to my girlfriend after they broke up. So his former gal is talking to me, and he's talking to my gal. SOOOOOOO to make a long story short... this gal said all the right things, told me he told her that Tara (my gal at the time) had sex with him.... got me all pissed, while telling me how hot I am... which did the trick. We ended up humpin' in the middle of a public park under a full moon.
It almost ended my friendship with my friend, because she went to him and told him that I said Tara and him had sex, and told her she was all hot and everything. Reversed the situation. We fought it out, me and him. Then after a few months, hooked back up.
The fucked up thing.... they got married. Still are, in fact.
Be careful.