@leanne66
From a clean, sober, recovering drug addict, I can say that until he reaches a place where it is either rock bottom or sees that he needs help and goes to get it, there isn't a lot you can do for him. It's like you are caught in the middle. You are conversing with him and conversing with mental health teams in order to get your son to help himself and the mental health teams to help him. It's pretty exhausting.
Maybe he is going to have to hit his rock bottom. Maybe he needs to not go for an assessment but a rehab centre through a drug program first. Perhaps that would be better suited as his drug usage is not over.
The voices he hears are his. At least that's what I think. Quitting us damn hard. It's a strong addiction but it can be done. It's a long road to recovery.
It would be hard to leave him to his own devices, but sometimes mother's can do no more. Perhaps letting him fall flat on his face is the only way he will eventually get the help he needs. Don't forget self care for yourself.
I hope something gives soon for you and him.