If he has the attitude that he can't control his reactions, then nothing is ever going to change. I'm not surprised that his mental health team has told him that they can't help him. A client needs to WANT to get better or they won't.

The truth is, that no matter how bad things are, someone almost always has control over how they react or treat other people. A verbally abusive rage? Yeah, he DOES have the power to control that and not take it out on you. He only thinks its an instantaneous reaction, but the truth is that there is a split second between the trigger and the reaction. He needs to find a way to identify that exact moment so that he can force a wedge between the two so it doesn't seem like an "automatic" reaction. It IS hard, but it can indeed be done. (I am recovering from PTSD and have had more than a few extreme reactions in my life. It is indeed possible to learn how to not react instantaneously.) Has your guy gone to anger management? He might find more help there instead of in just anxiety treatment.