I just finished reading the "dirt" post.
First, I would drop her like a ton of bricks.
Second, I wouldnt trust her as far as I could throw her (and remember from "first", she's as heavy as a ton of bricks).
Being taken advantage of is habit forming. And you've got quite a bad habit.
She is walking all over you. If I was her, I'd have little to no respect for you, which seems to be the case. I know those are harsh words, but it's the truth. I'm so sick of seeing guys getting whipped and abused, trying to be "a nice guy".
Stop any thought, right now, of becoming romantically involved with her. If anything does happen, it'll probably be because she needs someone to rebound off of. And you'll find yourself in an even deeper ditch. Some of those ucla girls are just a big piles of trouble, and anita seems like one of the bigger pile.
Another thing: dont let her call you out of the blues, and just copy your homework. I'm sorry, but no. If some random stranger in your class asked you to copy your homework, would you let him?
Treat her the same way you would to a guy who has made fun of and taken advantage of you ever since the beginning of your friendship. Just because she's cute doesnt mean you have to be her stepping stone. I'm sure if she was a he, you would've stop talking to her (him) a long time ago.
Not that I think this is gonna help. Which is really unfortunate. Most guys in your situation are thinking "I still kinda like her, maybe she's changed, I'll give her a chance, dont want to be a jerk."
Good luck
dfi