Hi Nic. Sounds like a pretty rough situation to deal with. Not something you can prepare for as it’s so random. I’ve seen many people before work alcohol issue for professional reasons.
How is he when he’s sober? does he regret his behaviour? I guess the big question is does he want to change?
I can see why you cant confront him this weekend. But you do obviously need to talk to him about his feelings about why he behaves as such.
take care