Big picture?
Expect him to drink again. At least sometime.
It happens. But they can fall down. And get up again.
But for best results he should probably at least try some long term program like AA.
And if you are going to stick around for the roller coaster ride, Alanon is a real good thing for you.
If he stay Dry AND Work a Program for a year or more . . . things can be pretty good. But that first year can be a long one.
Do you know where and how to get Alanon for you?