How to fight her

So this one girl keeps on bothering me. She tells me I'm a suck up, digs up dirt to casually use in conversation, and inadvertently insults me every chance she gets. But she does it in this cool tone, that sounds like she's joking even when she outright calls people slurs. In short - she's a *****. The problem? Well there's a few:
1. she's best friends with a friend I'm trying to get close with.
2. she constantly brings this stuff up In front of my crush, knowing I like him
3. She's friends with my crush
4. Even if I argue with her I have to sit next to her in 3 classes
5. Even if I confront her, she'll nonchalantly kick the accusation to the curb because 'it's just a joke' + She has established me as the 'crazy/delusional/book smart but street dumb' person at the table
6. She has a lot of dirt on me. A lot.
7. She's kinda scary. Like if I threw hands with her I would lose.
8. Confronting her would mean aligning myself with the undesirable people at the table who are basically the 'sensitive kids'
9. She's friends with some of my 'anti-fans' so I get a ton of rumors
10. She's occasionally really nice
..any ideas?

The best way to fight her is NOT to fight her; i.e. the best way forward is to not engage with all this petty **** from her and just act like a kinder, more sensible, more mature person.