When I tell him to leave, it's not a trigger. It more of a byproduct of my symptoms. I'm 100% convinced I'm no good and that he'll leave me eventually, so I need to act before that. Obviously, this isn't actually the case and I will never leave him, but it doesn't change that thought that comes into my head periodically when my symptoms are bad.

Honestly, I don't know what your son can really do in this case. She's convinced and sticking to it. All he can do is tell her he loves her and if she needs time, it's okay. He can tell her that he'll wait for her. Thing is, she really needs to get some help if she has these violent rages. It's not fair to him.