Ugh, I'm so sorry about what you're going through. It's hard for me to imagine the audacity of continuing to drink for a year after your family has asked you to stop. I hid my drinking for years, but as soon as the cat was out of the bag I went to rehab. I was a wreck but I knew I had to do it for them. And now I can't stomach the idea of relapsing, what it would do to them. That doesn't mean it won't ever happen, because I'm an alcoholic. But it means that I'm going to fight like hell for my sobriety because now it matters to my family, too.
The only thing I can imagine is that his addiction has progressed to the point where he doesn't care about or is numb to the damage he's doing. Which is terrible and sad. But in my book that means you should make the ultimatum, and then if he doesn't get sober (and within a set time period, like a month) you should leave. Maybe that'll shake some sense into him, which would be great, but if it doesn't you're still making the right decision. He's had plenty of time to make good on his intentions of sobriety, if he had any. After a year, he's adjusted to whatever level of humiliation or shame he feels from not having quit, and will probably be fine continuing that way ad infinitum if you let him.
I just know from my own experience that we alcoholics can live in a terrible situation for years at a time. I hope you don't put yourself and your kids through that when you have the ability to get out.
Good luck...