Mine used to give me that line too about if the tables were turned and I was the drinker it would be all rainbows and sunshine and pure glowing love coming from him. Yep heard all the time how super supportive he would be. It was just a big load of manipulation.
Nothing you do causes him to drink and unfortunately nothing you do will bring about a cure either. (He'll have to see LadyScribbler's ex for that. )
I'm sorry you are dealing with this mess. I think you are absolutely doing the right thing for your kids.
It's so challenging to stay the course at times like this. 2 years out and I still get guilt attacks. Nothing has changed for my ex but the kids and I are doing so much better.