She added me repeatedly. If she was at all annoyed, she could have just blocked me. There's no civil case when all the tools for removing you from a person are at your disposal.
I think threatening rape, torture, and murder goes beyond the level of a civil case.
Anyway, I agree it's best not to get the police involved in situations like this unless the person already knows your name and real address and is making serious threats. Even then there is no guarantee the police will do anything and the best course of action is to move under an alias.