This sounds so, so hard.
The bargaining seems to be a theme. Unfortunately, if there isn’t complete abstinence from gateway drugs like alcohol I’d be worried too. Like you say, it has to be his decision and it sounds like he’s still hedging his bets or but willing to accept he needs to stop everything and probably stay away from triggers including friends who use drugs.
I really hope you are doing as ok as you can be. It took so much for me to leave my partner and his children, and to continue to stay strong and not give in now we are apart. I hope you have some support from family and friends?
It is frustrating that the kids can’t understand. I wish you all the best and hope you find the strength to best deal with things in the best way for you and your children.
Stay strong and don’t feel alone or let yourself be too isolated. Take care 🙂