HELP ME

Me and my boyfriend have been together for almost 5 months now.

But there's this girl that asked him to kiss her and her friends also forced him to sleep with her during a trip...

I trust him but he also admitted he liked her before we got together; He says he loves me but he's not going to break up the friendship he has with her because she has been very sad lately since he's with me and not with her and he's sorry about it.

What should I do?

I feel so insecure and bad

I mean, Am I the one who should tell him she won't ever leave him alone?