Block him and all his affiliates on Facebook:
It can’t just stop at him. He will ask his friends who know you to use their accounts to spy on you. With the friends who he doesn’t think will say yes, he will just sneak onto their computers while they are not looking. And if he sees one guy post on your wall, or one picture of you looking a little drunk, or even just a sign of life, you can expect a nasty message or embarrassing wall post. Or, he might even track down a guy he saw post on your wall and threaten him.