Can someone like him ever get to the place where he sees that he was wrong, those things never actually happened? With the help of therapy, possibly. But not possible by himself, or with you helping him. That’s not an attack against you, he just needs a trained professional. Does anyone who’s there ever regain that much rationality? Possibly, but also maybe not. If he was a heavy drug user then its more likely he wouldn’t really regain it. I can’t give a good answer, I am not a professional. I do know that drug use seriously messes with the brain, and some people have serious, life long issues because of past drug use. He may be able to get better to some extent with the help of therapy and meds, but obviously any serious damage may just be permanent.