I'm glad you're going to Al-Anon. That helped me an awful lot. My situation was similar to yours -- my ex WAS drinking every day, but keeping a job and "functioning" on many levels for many years.
That makes it hard. Because I always questioned whether it really WAS as bad as I felt it was?
He would tell me how lucky I was that he didn't go out to bars to get drunk. He would tell me how lucky I was that he made so much money. That he didn't cheat on me. And for many years, I believed him. I believed that I was WRONG in being unhappy. That I didn't deserve more than I had.
I didn't realize that he set the bar really low for his own behavior.
The difficult part when you're married to an alcoholic who is still in the functional stage is that you don't believe your own emotions and eyes and experiences. You question whether you have the RIGHT to leave -- especially the father of your children.
I would like to welcome you here, because this is also a good place to be, just like Al-Anon. And when I was in your situation, I needed the support not just in meetings, I needed to know that there were other people on the Internet who could relate.
The tragic thing is that "functioning alcoholic" isn't a TYPE of alcoholic -- it's a stage. For now, your husband function. If he doesn't seek help, you will see more and more cracks in that functioning facade. Until he no longer does function. And seeking help is not something you can choose for him.
But you can get help for yourself. And you can get help for your children.