Just remember... No matter his words and actions right now. They are a symptom of the problem... Actually a reaction, too. The man is cheating sober, too.
So. For you and your family's sake, consider Al-Anon. But, do it in tandem w/the rest of your plan. His potential alcoholism isn't the problem, it's just the first one to deal w/in a possible reconciliation OR future in co-parenting.