How to get over ur man sleeping around during a break??

My bf and I broke up and I slept with his friend as revenge, we were on and off for about a year he went on a sex rampage to forget me but it didn't work so he came back to me. We reconciled. He came clean about what went on when we were not together. Everything except what happened between him and a female friend I didn't like to begin with. He was actually still hanging out with her and I knew about it but I confronted her cuz He told me she was talking badly about me for not wanting them to hang out and she gave him an ultimatum either he leaves me or she's not talking to him anymore. He chose me. Then weeks later told me the whole story and apologized. Since he and I got back together he didn't cheat on me and never cheated before. He told me about what happened when we were broken up but didn't wanna end the friend until she acted inappropriately when we got back together. I'm having trouble dealing with this. He was never the kind of man to act like that and  so when he went on this revenge I wanna get over u sex spree?? It floored me. I'm so mad he didn't tell me what happened earlier and that he waited for her to be inappropriate b4 getting rid of her?? I'm livid. He's being so perfect and b4 this we were happy. All I wanna do is kick her ass and torture him until he feels the way I do. But that isn't gonna help and I want things to work. How do I stop feeling awful?? R there any tricks to navigate through this easier??