My mom always said men fall harder than women. She should have known she dumped quite a few men in her lifetime.
The best tactic I think would be for you to ignore him. If he sends you emails, don't reply. Better yet block his emails and his phone number. That way you don't have to deal with him....hopefully.
You hear horror stories about men who feel scorned. Hopefully, he's not some nut job who is on a obsessive mission to win you over at any cost. If that ends up being the case, you'll need to get the authorities involved.