New to coparenting

My husband and I are separating. He’s an alcoholic in active addiction. Our kids are preschool aged. They are my world. If you have walked a similar road before me, please give me advice!!

What do you wish you would have known? What do you wish you would have asked for? What can keep the kids safe when they’re with their Dad?

I’ve consulted a lawyer. Looking for a worried mom/partner’s perspective.