punch her in the boobs....
"BAM!..........right in the baby-maker."
There is always the breakup sex...
Just because he stops talking to his best friend, doesn't mean he has to do something gay like have sex with him before they stop talking.
I eventually started talking to my friend, which he was still dating my ex...
I don't know how you could. He wouldn't be my "friend" anymore. No loyalty to me at all? If I liked my best friend's girlfriend, I'd keep my yap shut and just be happy for my friend and how he has such a fantastic girlfriend.