I'm so sorry to hear about this.
Now, here's an advice. Do what you think is right. Don't let
anyone decide for you
what you should or should not do! Not even that girl. It's your
life and your rights! Continue
being friends with the guy whom you know. Don't give up the
friendship. Every friendship is precious.
As far as I know, this girl is totally insecurewith herself and her
boyfriend. She should not be in a relationship at the first place!
The guy is also a dumbass for allowing her to take control of his
life. If I were him, I'll give that s.l.u.t. a boot manz! But
anyway, continue doing what's right. Don't let anyone control your
beliefs.
All the best!
S.H.I.N.