You know, it never quite made sense to me that you reported your family being so blase about addiction and substance misuse when you reported that they all drank "normally" and your upbringing was "good". Well-adjusted adults and parents aren't generally casual about heavy substance use if they have functional relationships with drugs and alcohol themselves. Things are somewhat clearer now.
And jesus, no, not everyone's Christmas is like that. I would have stopped fucking coming long ago if there was any significant chance anyone would end up incoherent or with their head stuck down the toilet. People might be slightly merry and free-flowing with talk and board games when the kids are in bed - that's the limit.
I can still remember the one time my dad got singing drunk after my brother's graduation when I was quite young. I was older than DD, but I was frightened and desperately embarrassed. I've never forgotten it. Drunk, stoned adults are terrifying for children.
red - your boundaries and expectations for him are much too loose. He'll do exactly what he's doing now - give just enough for just long enough until he senses your resolve has been sapped again. Then it's back to same old same old.
I'll admit, it can be very frustrating reading this thread. Not even because you haven't gone yet, but because you seem to be gathering resolve and actively planning, and then he throws you the merest bone and you lapse right back and defend him, and because your DD honestly seems to play little part in your thinking about this whole situation. But if it is helping you, I don't want you to stop posting.
It's becoming more and more clear that your family of origin was NOT normal, and that the normalisation of addiction and abuse began long before you met your H - indeed, that you picked him for a reason, as did your sister. Your DD's fate is becoming pretty clear too, unless you find the strength to end the cycle, get yourself into healthier surroundings, and get yourself some counselling. She'll become an addict herself, or choose an addict for a partner, or, if she's really lucky, both.
Call Women's Aid. Tell them you're not sure what to say, but a load of people on the internet tell you your relationship isn't normal and your husband is an addict who abuses you. They can take it from there. You know the Russian proverb, "If three people tell you you are sick, go to a doctor?" You are sick. Get help.