You could suggest a dual diagnosis worker who will work with both the mental health issues and substance issue. Has he got a care coordinator?
It’s so difficult to manage an opiate addiction. Have a look online at “Ben’s story” it’s about a life of a heroin addict.
I would think he needs to get on a therapeutic dose to stabilize him and then the using on top should reduce. Does he use other drugs also?
You would need to take care of yourself also so have you tried al Anon? Look them up for a group meeting. They help families.