I don't know the whole situation, but if it's as bad as it sounds, she can't stay in that environment. You probably have guidance counselors at your school, go in with her and have her talk to them. The dad sounds like a real ass. Depending on the extent of the abuse, he could have a serious legal problem on his hands. The only solution to this problem is to remove her from this environment. It seems the father is the cause of the issues, so really you just need to get rid of him. It sounds extreme, but if the guidance counselors think it's a good idea, this should be brought to the attention of the police. A situation like this will continue to spiral out of control if you don't change it, in both the physical dangers at home and the mental issues.