Hi, Lorri,
Being an RN (check) and being over 50 (check) and really smart (check) does not insulate us from co-dependency. He's dependent on alcohol, you're dependent on him.
I walk the same road you do, and IT IS HARD. Ultimately, you cannot control his behavior, drunk or sober (or dry drunk for that matter). Also, not every unpleasant personality trait is due to alcoholism. Plenty of sober folks have issues too.
Good luck, I know this is painful.