Suggestions? Abused 14 year old girl?

It's people like her that I don't think can be changed and no one knows why they are like that. Just endure a couple mores years and then move so you can lead a happy life without abuse. Don't try to make someone like her like you, it won't work. My best advice is talk to a couselour, principal, or teacher about it so maybe your mom will notice what she is doing and STOP.