Should I drop my best friend?

Brie, my best friend, ran over me with her car on Sunday. It was an accident, but it happened because she was messing around, and sped up while backing out of my drive way as I went to grab something. I've told everyone that she didn't see me. But I KNOW she did. She denies it. While I was at the hospital, in unbearable pain, holes in my legs, gashes all over my body, she texted me asking if she could use my hair straightener. She says she got a black eye when she ran into my house to get my parents, she wanted to make up a story saying I punched her so she ran me over. She laughs and jokes about this all the time. I can't walk, pee, or shower without help. She laughs at this. She has always been a terrible friend... But I've always put up with her. This seems to be the worst thing she has done. I want to drop her. I just don't know if I should, or how to do it. I don't want to piss her off, she might egg mine and my boyfriends houses again....