Sounds like a complete pyscho to me, probably has communication problems too.
I kinda acted like the way this creepy person does when my gf dumped me, except i was like it to everyone. I think i acted like that out of anger, that my happiness was taken away and no one was even attempting to help me through this rough period of mine.
But then i came back to earth and started being nice to people again

but what i found was that i was becoming really depressed instead. I saw a vicar about it, and he said "
anger and depression are the same thing, except one is directed out to the world, and the other is directed inwards".
It sounds liek this creepy person has alot of serious issues and social deamons, and alot of paranoia. I passed that phase about 2 months ago, and have never been happier

but i was alone during my creepy time. very lonely.
the best thing you can do is let him be, try and avoid him, he'll come to his senses one day, and if he doesnt, who cares? I'd seriously consider cutting him out of your life.