Honey. Right NOW, you go find one of those PMs, and you DOCUMENT it, and you reply with this statement:

The next time that you contact me, I will contact the police. I do not wish any futher contact from you, of any kind. I consider your behavior to be harassment. I do nto want to speak further with you, I do not want to explain, I do not want to be friends. I wish for you to NEVER contact me again. If you do, I will consider it a threat and contact the police.

This is nothing to fool with, and nothing but a direct, blunt, ABSOLUTELY DEFINITE AND FINISHING STATEMENT is good enough. I mean it, rapes are done by people that the woman knows. Put a stop to it now, I cannot stress that enough. TELL YOUR PARTNER. Be sure your partner knows this guy is out there and stalking you. Be sure he knows that a stalker will do or say anything to destroy your life.

And I cannot say it with enough conviction, or with enough force, or enough emphasis. WARN HIM to back off, TELL THE POLICE, and if he contacts you again, GET A RESTRAINING ORDER. Accept that he has crossed the line, the friendship is gone, and he is now like any other criminal. Take that into your mind, and embrace it. HE dropped the ball here. You are worth taking good care of, so go take care of yourself. This is serious stuff, ex friend or total stranger, creepiness is creepiness.

If you feel alarmed now, good. If you don't, you should. Take this serious, it is.