I don't understand why you keep calling HIS sister, his family. You do not have a "bond" with these people. He contacts you, threatens you, acts like a drunk fool in public, the only person you call is the police. PERIOD. You keep yourself tethered to him.
Believe me, he sees that he has a way to tie you to him, the phone, the sister, blah blah blah.
Cancel the contract and be finished. You don't owe him anything, you have enough to remember him by, like the maxxed out credit card you are paying for.
exactly get a RO and don't violate it. You can never move on with the constant contact to his family. He is NOT your responsibility, he is an adult, you have no special magical power over him to "calm him down", unless you are feeding your own needs.
If you are really done, than be done....