Is he on medication? I know the WAS's are loopy, but he sounds a little off to me.
If he's in that frame of mind, I'm glad he's not watching the kids.
Maybe you need to employ the warning system. Warn him once about yelling.. if he does it again, simply hang up. No discussion for an hour. Give him time to calm down and maybe screw his head on straight.
Sounds like he also may be trying to get some reaction out of you. Wonder if his family laid into him and he's acting out.
