Hi Jane, even though your mind is in turmoil, it seems pretty clear what you want. You've already made up your mind, and it's just the guilt and fear of telling him that's holding you back. You could do the therapy, pretend, go through the steps, but the outcome will just take longer than it should.
It's kinder to him for you to be honest. If he relapses, that's his business. You didn't cause him to drink before, and you can't control it now.
You have a dream of how you want your life to be. Go for it!