Advice??

Skeet

So I have this friend sarenna that I met around September of last year and we automatically clicked. Me and my boyfriend have been running around with her for a while now we party a lot. At the beginning of me and my boyfriends relationship, the friend Ive been talking about my boyfriend and a couple other people got really really really drunk like falling down in puke drunk, and the next day my boyfriend had a hickey that wasn’t from me I found out it came from sarenna. I ended up forgiving what happened because I’ve don’t stuff I’m not proud of when I was drunk. We’ve been friends ever since sarenna and my boyfriend ended up becoming best friends and so did me and sarenna but we’re not longer best friends anymore, we’re still really good friends and hang out all the time we’ve been through a lot together this past 8 months. It’s hard seeing my boyfriend and the girl he cheated on me with be best friends because that come with jealousy and problems but I trust my boyfriend with everything in me not to do anything with her. Lately she been being fake there’s way too much to explain what’s going on but it’s enough that I’ve decided I don’t really want to be friends with her unless things change. What the best way to put it?