@Freddie15VES that made me wonder if it's some sort of alcoholic bargaining – if I do X, Z and Y, I can have a drink to reward myself.
My mum used to do lots of painting and decorating – badly. I used to be bemused that someone with such a neat, controlled hand did such a messy, slapdash painting, barely using masking tape. Took me 20 years to figure out that it was her rushing through things to get to her drink. (That's a minor confusion from growing up with an alcoholic parent – it got worse than that.)
However, we are getting into detective work here, and ultimately that doesn't help.
He's in a bad way, but it can and most likely will get so much worse, I'm sorry to say. I'm really sorry you're in this situation but the advice you've been given upthread is correct. I wonder if it's worth talking to a solicitor (I don't know if Citizens Advice can help here?) to help you figure out your next steps. He may be able to change. I hope so. But he can only do it himself, and you need to put yourself and your children first. They will be affected by it, and they deserve a happy, stable home. So do you.
(Oh, and you're not a bad mum, you're just a person who's trying her best, who is baffled and heartbroken by the pain of living with an alcoholic. Here, we all know what that's like. Those who left the alcoholic, or lost them in other ways, will tell you that as much as it hurt, a peaceful life is a good life.)