If the ol’ nape slap didn’t do the trick, nothing will.
I have a “friend” just like this. I borrowed some money from him and he uses the fact to try to get me to do all kinds of free work for him in addition to the payments i’m making as agreed; along with his racist and conspiracy theory laden ideas. He recently tried to order me around and I said no to him; this caused him to make comments about how I was ungrateful to him because I wouldn’t jump to his beckon call. If he doesn’t want me as a friend anymore, I can live with that, the friendship seemed all one way from my end.
It may not be easy, but poison people aren’t worth the aggravation they cause.