When you say that it seems "better" for the kids to stay than it does to leave, you are also making that assessment based on how things are at this moment. Alcoholism is progressive, and it tends to progress slowly, by degrees. By the time you realize how bad things have gotten, a lot of damage can be done.
I'm not saying it's impossible for kids to grow up as reasonably happy, reasonably well-adjusted adults with an actively drinking alcoholic parent in the home. Based on what I've observed, the odds are heavily against it. I guess it comes down to Dirty Harry: "Do you feel lucky?"
None of us has a crystal ball--if we did, life and its many difficult decisions would be a lot easier.
You don't have to make any decisions this minute. But I think getting involved in Al-Anon could help clear your head so you can see what's going on with a clear head and make the best possible decisions when the time is right.