Lynn,
I was wondering if you thought about calling CPS (or whatever it is in your state) to report the behavior of the girl. I know that schools are supposed to report suspected abuse, but they often do not. You can report it anonymously and let CPS decide if it is something that they should follow up on. It just makes me think that this girl is experiencing something bad at home and was acting out. Please think about it.

I think you did a great job dealing with the situation.