[Advice]Breakup advice?

Backstory: Brandon, and Crystal have been dating for several months, and Crystal had been involved in our friend-group for several months before that, because Brandon wanted her there. No one particularly cared for Crystal, but we all tolerated her for Brandon.

The People: Myself: Anti-Crystal, Long time member of friend group Mary: Undecided, Long time member Jerry: Undecided, long time member George: Pro-Crystal, short time member John: Anti-Crystal, long time member Brandon: undecided, long time member

So Brandon and Crystal had been dating for a long enough time for Crystal to squeeze a place in our group, but then she broke up with him. The last time this happened it was with a kid named Mark. Mark was the nicest guy ever, he was a perfect BF, but she obviously broke up with him. This completely broke Mark, he still isn't over her, and it's been a long time now.

Despite the fact that we all liked Mark better, she stayed and he left. So now we have to make a real decision, and talk about what to do about Crystal. She is a horrible person in general, really mean to everyone, especially Brandon.

The main reason there is so much talk about this is because we are worried that asking her to go would cause tensions, as some might support her over Brandon. And to make it worse George has a thing for Crystal, and may have had a hand in the break-up.

Any advice on how to deal with this?

(All names are changed, and if you want more details I'll put them in comments at request)