How do I forgive and move on?

I am feeling so much anger and I can’t let it go. My boyfriend had a girl-friend that tried to fuck up our relationship more than once by lying about me and other stuff. My bf stopped talking to her but she’s still in my group of friends and I feel sick to the stomach just thinking about it. I really hate her, I can only think of ways to humiliate her or hurt her and its driving me nuts. I have even considered ending the relationship because I just can’t deal with all the hate I’m feeling because at this point I’m the only person being hurt by the way I feel.

What should I do, how do I move on? Thanks