Ex best friend.

I'm sorry - I need to rant - this is driving me mad.
I'm 18, go to college, have autism but its not noticeable, normally very cheerful.
I had a best friend who was like a parasite. Seriously, at the time I put up with her because she kept telling me to my face she was my best friend, but looking back, she treated me as less than human. She'd mock me for being a veggie, poke fun at the way I look, my music, my art, my hobbies (literally, everything I like is "shit") and put me down at every opportunity. She CONSTANTLY accused me of things I hadn't done, called me a liar, a cheat, told me my autism would scare men away and essentially made me feel crap.
So now we've fell out, why cant i be happy?
Essentially, i had to stop home and work on some college work, and when i hadn't been out for a couple of weeks, she accused me of deliberately ignoring her, which is the standard. Note that she will ignore me for weeks on end and then emerge when she needed me, but when its her its different.
I told her I had work, and she said that I had abandoned her for my new friends (by "new" friends, she means the ones I've had for around 2 years who treat me like an equal human being and actually make me feel loved). When I explained I hadn't been out with ANYONE for ages she literally put (I remember it exactly because of the sheer embarrassing wankyness of it:) "My ears are bleeding from all the lies".
I have NEVER lied to her in my life.
She has lied to me more times than I can remember.
she then did the usual and slagged me off for five minutes before signing off before I could put anything back. Like the mature 19 year old she is.
She has now blocked me on MSN, removed me off facebook and cut me out of her life.
yeah.
I should be happy. She cost me hundreds in borrowing money off me, she put me down, and worst of all insulted my Boyfriend. So why cant i let it go? I'm so angry and hurt. I just want to forget her.