I'm sorry you're going through this!
The only thing I could think of is having a private investigator (or friend) video tape him when he's drunk; you can set up cameras, and have the current day's news paper showing at some point, and even the day's news playing - then as he acts drunk and slurs, you'll have proof of how he is when he's drinking. Can you get affidavits, too?
I'd say this is deceptive, but nothing is too deceptive to protect your children.
Good luck and think with your HEAD and not with your heart. My ABF has been to the hospital twice for smoke inhalation because he was cooking while drunk and fell asleep. He also flooded an apartment by letting the water run in the plugged sink. I think about that a lot - when I consider standing by him.
:praying Praying for you and your family's safety.
R.