If you want a breakup and he says "no," doesn't that seem odd to you? If you want to break up, do it and completely ignore him. Is this the same guy who dumped you after taking your virginity?
Get rid of him; he sounds like real bad news.
If you live with your parents, tell them what's going on and stop taking his calls.
If you live by yourself, have your best friend come stay with you for a few days and do the same thing, ignore him.
If he becomes threatening, CALL THE POLICE. They're nice folks.
You could be saving yourself from a bad, bad relationship by listening to your bad feelings now.