This may be as good as it gets. Are you prepared to settle for that the rest of your life?
You didn't cause his addiction, you can't control it, and you can't cure it.
The drugs were only a symptom for me. I had underlying issues that drove me to use, and until I addressed those issues in an active program of recovery, I was never going to get better.
Educate yourself on addiction, and get help for yourself for the effects his addiction has had on you.