@Sh0w me,
Ah, she's a social climber.
But you're in a bind, as you say. Have you tried to talk to any of your teachers about this? Not to complain, more to point out when she's behaving in a way that doesn't reflect the kindness, etc. that she's faking.
You won't
really know how the teachers feel unless you ask one, or at least clue one in. Most of the teachers are likely to be seeing through her nonsense. They all know a suckup when they see one—because teachers see one in pretty much every graduating class.
But there can sometimes be external pressures you don't know about. If her parents are wealthy, they could be leaning heavily on the school to give her an award so their precious darling will have something or other to put on her college applications.
Anyway, getting back to talking to a teacher: it may help you in terms of bouncing her out of the group without being dinged as bullies (zero tolerance is a stupid, unimaginative policy, thought up and enforced by people who have as much imagination and flexibility as they have tolerance). It can help to have a teacher advocate who knows that she's the problem and not you.
You should have the freedom to be able to socialize with whomever you please. While the school may want the student body to all get along so as to prevent fights, this doesn't reflect reality. People are allowed to not like each other. They are allowed to drift apart. And you're entitled to not have to kiss up to someone who treats you like something they found under their shoe when the cool kids are around. I mean, who's the bully in
that scenario?
Another thought (although it would take finesse and may be hard to pull off—and I don't want you to get in trouble) is to make it (a) attractive for her to hang out with others and (b) less attractive and comfortable for her to hang with you.
Presumably the school year is coming close to an end so you'll be free of her for a few months. People can change, and maybe she'll stop trying to keep up with the Joneses and realize other folks have value, and not just as last choice ports in a storm when she's got nothing else going on.
One can only hope.