My brother died at 57 from alcohol.
There is nothing you can say, do, threaten, bargain, manipulate, plead, shame etc that will get him
to stop until he wants to stop.
The church allows separation for drunkeness.
Tell her to take the children away from him
Then pray for him.
Well said. Support isn't support for a drunk, it's "enabling". Tell him to pray the Rosary, three Aves, something. He likely won't now, but may later AFTER the pain of loss is greater than that he's drinking away now.
Support HER. Help HER, so that she can do the right thing, including pray for her husband. After that, he'll either get it together, or he won't.
Caveat: don't assume that demonic isn't at play here. If available, and being a lush seems like danger of death to me, they can last ditch try to avail themselves of whatever VALIDLY ordained priest, preferably traddy, preferably (don't hold your breath on this one) an exorcist just to check the boxes if naught else.
Prayers: Blood/family in particular can do bindings/adjurations/abdurations.
Basics: Are they Catholic? Are they baptized? Has their environment been blessed, consecrated etc. etc. etc....