Dear "tired":
Sorry you're going through this.
I can't really add to what "isurvived" said. It's hard for us who don't have an addiction to alcohol to understand the addiction--it just feels like the addicted person is messing about and being mean for the sake of being mean.
I do rather think that it would be better for the kids to have a degree of separation from mom if mom's drinking is making her a danger to them. And it doesn't have to black or white--they could see that dad is taking a firm hand and keeping them safe (by separating from mom, moving into a new place, etc.) and then at the same time they could have contact with mom on a regular basis.
Take care.