Sadly you know this but he’s not going to stop and will continue. I’m sure you love him deeply as my wife did me but you need this advice. Moving to the next step is the only thing that will really help him because what your doing now has become acceptable to him.
No one can force you to get out but it is probably the only thing that may help him. I know you will be thinking about this the same time next year, the next 5 years until the worst. Help him by taking ACTION. He’s an addict and that’s how we work and unless he commits to reality and has regular treatment and drug testing then it will never work. He maybe attending but he’s not listening. It’s really hard to break away. Ultimatum is a horrible word and love has no limits.