Use a blocking function on your e-mail. If you don’t know how, telephone your internet service provider and ask them for help in blocking his e-mails. Don’t take his phone calls, and if you don’t already have it, get caller i.d. In fact, call your phone company and ask them how you can block phone calls from his numbers.
If you stop engaging with him, he’ll eventually go away.
I hope that helps. 🙂