i've been in similar situation, she had sex with somebody I do not know by the time we were FWB and I allowed that to happen.
I don't think I would be as affected if it was some of my friends, because the idea of not knowing who/how, that was what was killing me, but AFAIK she never did that with my friends so I do not know the feeling

At first I showed that I did not like it (fail), later I started keeping my frame. Still remember it from time to time though.
You are jealous about particular person. Is it actually because he was somebody you knew or it is just because he is a douchebag?
Not to make you feel even worse but I have a feeling that
Quote:
She probably hooked up with more than just that guy
that might be very likely.
But again whats done thats done. Man up somehow. Fuck her hard like you never did before, and think about it as a punishment. Be dominant and kind of positively angry. This will make things easier inside you, and she will probably like it as well.