For one, if he calls, hang up on him. Next, get a restraining order to get him to either back off or get the law on his rotten tail. That way, he can go do something else instead of being obsessed with tormenting you. He frankly sounds like a shithead that could turn into a stalker if you don't stop this.
So call the police and ask how to set up a restraining order, or simply ask them to go and check him out for you. That alone might get him to back off. Most such jerks are cowards who get scared if somebody else confront them on their lousy behavior.