I agree with Best.
I think we sometimes get confused about what we should and shouldn't do b/c we (at least I was) are used to yelling, threatening, trying to shame, giving the silent treatment etc. and we're not supposed to do that.
But we CAN set boundaries...of what is and is not acceptable to us, and they must be enforced or there is no value in having any.
His actions DO affect you (Christmas), so a boundary could be something like telling him if he chooses to drink and drive again then the consequence will be __________. but don't state a boundary unless you're prepared to follow thru, otherwise it becomes an empty threat.
All the best, please let us know how you're doing.
((hugs))