Okay. Before I am flamed please read this disclaimer: I am probably wrong. But just in case I wanted to offer my experience.
First of all it sounds as though you are both very unhappy. He sounds as miserable as you.
My mother's advice on this one would be "pick your fights". Why organise an intimate night when he is having a leaving do and you know he can't say no to a pint or two. Some might point out that it was almost perfectly set up to fail.
Secondly. Do NOT argue with a drunk. It is pointless and dangerous and the children should not be subjected to you and your husband's shit (easier said than done).
If he ever leaves again let him go. Never ask him to return. Unless you are actually in the wrong.
If you believe he is actually an uncaring bastard incapable of being a good partner or father ask him to leave.
If not, get counselling. I think it sounds like two people at the end of their respective tethers.
If I were to imagine for a moment. You have a style of arguing which heaps on criticism. Hyper critical style. I have one of those learned from my mum.
He has a "I'm out of here" approach to arguing (apart from when he's drunk). My dh also has one of these.
My dh also carried on with the partying after the kids came along and we had this kind of awfulness, although he never shouted at me. It only ended when I drew the line. A life apart is much better than a life together like this.
You are not communicating. He is not listening. If you don't learn to communicate you will split up.
I am not sticking up for him or excusing him. He is behaving like an arse and when my dh was like this I sounded like you, angry, defeated and sad.
Draw the line this morning. Set out your needs. My number one would be counselling. Do you have good parents or does he have decent parents who you could involve for advice/mediation. I involved mine and they really were great.
We got through it and have emerged happier and closer. The kids have a great dad (not the hungover half ass). We don't have these arguments any more. He doesn't choose drinking over us anymore.
I think there are many couples going through the same struggle with alcohol. It is a big adjustment. My experience is that woman tend to get things into perspective and under control during pregnancy and things do change enormously. Mat leave. Bfing. Sleeplessness. While everything just stays the same for men so they struggle with the transition. It would be great if all men handled it perfectly but in my experience they don't.
Sorry for being so long. I just felt a familiarity to your words and wanted to let you know of an alternative to ltb.