You did absolutely the right thing keeping him in on NYE after he came home in that state (thank goodness he was brought home). You were then treated very cruelly and utterly unreasonably. I guess you realise that it was the drink (a hell of a lot of it) talking? How do you usually get on with this DS?
His pride is obviously very wounded, hence the defensive attitude now, but you're doing the right thing by setting boundaries. Your DS is a child, an older child, but a child. He has GCSEs this year? Or is in sixth form? Either way, the timing is crucial and he's got to get things together. School any help at all?
If your DS mostly lives with you, don't you set the rules re the weekends and weekdays? And you're right - your younger children are very important and nothing can be allowed to compromise their stability.
If it's any consolation, my DCs (actually two of them at various times) have reduced me to tears. When they decide to be unkind, god can they dish it out. You're not alone. I agree with Silence, wait a day or so, if you can, and talk and set the ground rules. Perhaps when he's sobered up a bit, or is generally calmer, he can actually work with you in negotiating them. My DH tells me that our kids lash out at me because they're very close to me - so I'm a sort of easy target. Doesn't really help but I think I see what he means.
Good luck and try to be hopeful - he is very young.