Help me with this girl at my school!?

This girl must feel very alone. Just listen to her and try to understand what she's going through. When she's ready to admit what's really been going on at home she will...on her own terms. Be patient, try to not get frustrated. You could suggest her receive counseling (she might want you to go with for moral and emotional support). Personally I was only physically abused by my mother. If the abuse ever reaches a physical state call 911 and they will contact CPS (Child Protection Services). Depending on the cirstances the police will remove her from the premises and both mother and daughter will receive counseling provided by the state.