The best thing would be to talk to a counselor, the city/state should provide some assistance, there's programs everywhere. If you don't want to go that route try some websites like this one:
http://www.couns.uiuc.edu/brochures/friends.htm
Also talk to some law enforcement officials or a lawyer to find out what kind of evidence you would need to convict the motherf*cker and send him to jail, or at least get him some mental help.