Nothing changes if nothing changes. I think the Alanon meeting is a great idea. You don't have to lie. Can you just say "I was at a meeting." And leave it at that? Why are you scared to tell him you're going to Alanon? Are you worried about how he will react? Will you get interrogated?
There's nothing to really be gained by confronting him if he's not ready to quit and you aren't willing to enforce a boundary.
Some areas have lunchtime Alanon meetings so you could go during the day.
I painted myself into a similar corner with my ex, making all my options seem impossible. The truth was, I had lots of choices, I just didn't like them so I hung on and kept hoping something would get him to change. It was a long wait for a miracle that has yet to manifest itself.
Please consider going to Alanon. Those meetings have helped me immeasurably.