<human>: Summarize the given text in a few sentences.

Where to start, I met her about a year ago just at the start of collage (UK) and from there I thought she was perfect pretty much fell in love with her right there and then. I also met her best friend and another guy and we quickly became best friends as a group meaning the whole relationship revolves around the group sticking together. We go on double dates with the other two and we go on our own days out and meals out for example. Around Xmas time last year, we got with each other for the whole night, we stated the next morning that we both neither regretted it and carried on, from there we talked every day for the year, easily every day. I really felt it was going one way we began to flirt when texting and I began to really understand her. 

She also told me about her abusive ex who is also smokes weed practically every day. The reason their relationship broke up before I met her was because he basically tried to force her to have sex with him before cheating on her with another girl. He emotionally tormented her before she said enough and left him.

Today she told me that she was trying things out with him again after she talked to him at a party and that she now things he's matured and is going to see where it goes she said she had to tell me because I'm her best friend basically.

The issue I have is, I don't want to hear or see him with her because I literally want to rip his head off, I'm finding it hard to be happy for her because I know it will end in tears once again and finally it's basically turned me into a wreck but I can't cut her out of my life because it would split the group dynamics. But at the same time I don't want to let her go, ever. I don't really know what makes sense out of it all I just know that I want her back and away from him and I don't know what to tell her or do.
<bot>: My best friend who I've basically fallen in love with over a year is returning to her ex who tried to force her to have sex and then cheated on her, and I can't cut her out of my life.