My best friend is kind of a jerk?

So, my best friend is kind of a jerk. Some examples? Well, on my birthday she called my mother an old hag to her face because my mother said she was a red head (she is a red head). Also, whenever I get something like a new shirt or shoes I show them to her. I say "I got new shoes!" and she says "uh-huh..." I expect her to be excited and tell me they look good. I always act excited when she gets something new (even though her taste in clothing is not very good), and I'm still a good friend to her. When she comes over to my house, she is always acting bored and I ask her what she wants to do and she tells me "No, i'm fine I'll just read my book..." So irritating! Also, she called me a b**** and flipped me off. I told her not to do that and she said "You know how i get when I am upset!" There are many other examples but these are only a few. I really want to end the friendship but I can't imagine what she would do to me if I did. As you can tell she's a very rude person. What should I do?