Woof, using or not it just is what it is. I think that when they stop drinking we think everything will change. Or we blamed their bad behavior on the drugs and think they'll be better when they get clean.
Sometimes they don't. Sometimes the brain damage done by using takes years to heal and be normal again...and sometimes that just doesn't happen.
I don't remember if you've been to meetings or not, but if not maybe give a few a try. That's what helped me regain my balance and I know it can help you too.
Take care of yourself and your child, and let his HP take care of him.
Hugs