ML,
Welcome my friend!! You sound amazing. I wish when I walked in these walls 2 1/2 years ago that I had your clarity and understanding. You have been doing a lot of work on "yourself" and it can show.
I second the attorney. Where I live, first visit is free. Take a million questions in there and take advantage of it. Are you able to sock away any money that you can put towards rent? Also, If you can, I would take copies of all important documents because once you are gone, I am sure he is going to be pretty pissed off and won't let you in the door. Please keep notes of things that he has done, and dates, as this can always help in the custody battle. Can you pack any stuff and take it to a friends, very slowly he won't miss things, especially if he is always drunk.
I see that you are attending alanon. Are your kids old enough to hit any alateen meetings ? They are really good for young adults trying to comprehend the dysfunction in our homes. I hope that you will have their support to leave.
Stick around and keep posting. Many have walked in your shoes and are thriving. Sending hugs to you and your kiddos!!