Need help from unhealthy clingy INFJ

Beautiful INFJ's,

I know an INFJ who I used to be friends with. He's really unhealthy and immature, so don't think I take his behavior as a representation of all of you.

Anyway I invited him to a birthday like, 6 years ago. Since that day he considered me one of his best friends. As such, I've become very aggravated by his behavior as we got to know each other. I'll spare you the details as they're irrelevant. Basically he's a prick, and I've told him to leave me alone and never talk to me again. However, I am friends with his friends, and I have blocked him on every single medium possible: instant messenger, facebook, email, etc. When I block him, he'll go into his friend's accounts and start talking to me through them, e-harrassment. Everytime I invite over my friends (the ones he's friends with too), he comes over with them.

I want to delete him from my life. He doesn't respect me, or my personal space, or anything I've ever said. He knows he'll be able to contact me so long as I'm friends with his friends, and I've actually blocked my friends (they're ISTP's, they'll live and forgive) just so he would leave me alone.

Is there some way I can tell him to fuck off that he'll actually listen? Or do I need to meet him in person and beat the shit out of him until he gets the message? I'd prefer the former. Any suggestions?