What do i do with this "friend" of mine?I cant deal with her anymore....?

Your mom is right about not hanging out with this girl. You hang out with her and you will get her reputation. Please listen to your mother! What kind of girl would be asking questions about your own father with the reputation that she has? She does not need your help turning her life around. She made her bed now let her lie in it. And certainly don't feel guilty about it. Do you want her hanging around so she can come on to your father? Dump her.