First, let me express how deeply sorry I am to hear this happened to you. Secondly, let me say to you that you took the right course of action; telling your mother was the best thing you could have done at the time. Hopefully, your mother will stay away from him and, ideally, call the police about him. In fact, if he IS dangerous, her calling the police is a necessity.
I wish I could think of more to say, but I really can't at the moment, unfortunately.
