Has he been evaluated by anyone? I mean a full evaluation-- probably by a neuropsych or someone like that? It sounds like there is some kind of dysregulation at play, rather than "just" being highly gifted.

I would make sure that you are getting that evaluation to find out what is going on with him, because that will give you some tools to help him manage better (and probably tools to help all of you manage better)!

This must be so frustrating; he sounds lonely, and you sound so very sad for him.

Schrödinger's cat walks into a bar. And doesn't.