Bloody hell OP! There is absolute zero excuse for any of his behaviour, I was hoping in some small way he’d arrive late last night full of apologies.
Can you stay with family for a few days, ask someone to come and pick the 3 of you up?. No way I’d be staying if I had another option. Call the midwife and give her your new address if she’s due to come out today, and you can talk to her when she comes.
As his Mum thinks going out was ok, I’d also call her and say you’re leaving, that she should go over to see the state he’s in.
That normally you wouldn’t leave him in such a state, because you’re an adult who isn’t a selfish dick, but now you know it’s totally ‘normal’ / ‘expected’ to disappear to celebrate the birth of your child, that’s what you’re off out to do.
Then leave with your family or friends, and switch your phone off.
I’m not sure tit for tat behaviour is the greatest way to solve problems, but in this instance you can’t stay in the house with him vomiting everywhere, still falling down drunk, when you have 2 children
I truly hope you have someone you can call - even if you only stay out for the day. x