Drag him into some form of counseling that is familiar with PTSD. I went in with my husband and also had sessions alone. We still do that. I think it is the best thing you can do as a good therapist will never feel like he is doing "wrong", but there are other approaches.

Your hardest task will most likely be getting him to a doc. (I remember claw marks on the door as I was dragged) figuratively. There is light is he wants it but he must want it. You by the sounds of it could hang on a couple more years it takes for counsel to work. But there is no magic button. Maybe refer him here too?