I could really use a hand.

There has been this user who has been really awful to many users. He says awful things through PMs (I have since blocked him) and in the 回答 section and then deletes them so he can't get in trouble. And when myself and other users try to defend ourselves he threatens suicide または self harm. As far as I know this is a serious form of psychological abuse. link (replace "if あなた leave me I'll kill myself" with "if あなた fight back I'll kill myself" and あなた have what he's doing). And he has pulled this very stunt on quite a few users. link

I've already reported him so have others. But nothing is getting done. He makes me extremely uncomfortable and I don't know what to do about him.
I told him that we can just ignore each other but he keeps making 質問 about me and commenting on my stuff. And if I say anything back he pulls the "I'll cut myself" card.

I'm really stuck here, please help.