Is it normal that my best friend and i are drifting apart?

Lately, my best friend doesn't seem like much of a best friend anymore.

All that she ever does now is insult me, bully me, and basically abuse me.

Most of this began last year, but I tried to ignore it because it wasn't as bad as it ended up being this year. This year, however, it's simply unbearable and it's hurt me enough to cry every day after school this week. I'm not even telling my mom what's wrong, because truthfully, she's not all that good with sympathy.

For example, my best friend ditched me twice this week, and basically treats me like a dog. She smacked my hand today when I tried to point out her spelling mistake, and she's ALWAYS talking about her new outfits, but rarely caring about mine.

I used to think of her as my best friend, but now I can't help though think of her as a spoiled brat. She thinks that she can get away with anything just because she's her. She's always abusing me in every way possible (physical, emotional, etc.,) and is really ruining my life.

Along with that, she's turned nearly all of our old friends away from me. She does it subtly, and it really, really hurts that no one knows who she really is. No one knows that the class teacher pet is someone who shoves her best friend during a game; no one knows that she's someone who plays nice and then physically abuses people. No one knows just how much she insults me, and it hurts.

Is this normal, or am I the one being a spoiled brat?

Please, help me figure out a way to ditch her tomorrow. Please.