Good for you.
My father is an alcoholic, and my mother left him when we were 7, 6, and 4. It was the best thing she could have ever done for us.
At that point, we didn't know anything about it -- I remember that we had to go to bed waaaay early a lot of nights, and Mom would let us play in our rooms until we got tired. Years later, she explained that he had started drinking and she didn't want us to see him drunk. We never knew at all back then.
He married a woman who is a total enabler - I remember going to visit them (summer for two weeks, every other Christmas, etc.) and she would buy beer on sale and hide it under beds, etc., because he could go through a 24 pack a night and still be pleasant and conversational. He's switched to wine these days, but God help you if he gets out the liquor. He's a nice drunk, but he's still drunk and slurring and stumbling.

We all figured it out after the divorce, but my mom protected us from the knowledge/experience beforehand. Leaving him was the best thing she could have ever done. Life was difficult after that -- she had been a SAHM for 8 years and had to start a career over, etc., but she did and we were much better off than if we had stayed with him. Life would have been much easier financially, that's for sure, but I have a hard time imagining having friends over, playing sports, etc. and everything with him drunk every night.
Divorce is not easy - I don't want to minimize it - but it was so much better for us than staying with him. My dad is a wonderful guy, but he is an alcoholic, and alcoholics can't be healthy parents.
Blessings, mama -- it is so different for every family, and I don't think there is one hard and fast answer -- but for us it was best that she left him, and I hope you find peace and strength in your decisions. I will pray for you.