I can't stand this girl !!!

Soooo there is this girl who is friends with my bf, the thing is she has been the reason that a guy cheated on me before. My bf knows this but still talk to her I get sooo mad just when I hear her name I swear I have never hated anything like this chick... I know I can trust him but damn I really just wish she could disappear... What can I do to get over this hate feeling ?