I think you're putting too much stock into him "seeing the light." How is him going to ONE session going to show him how his drinking has affected you? You said you've been together 25 years but ONE session is going to show him? He can't see what he doesn't want to see. He isn't ready. By thinking the way you are, you're trying to control something you have no control over. You're hurting yourself by asking and asking. He's given you his answer....it's no. Quit thinking you can change his mind....quit putting expectations on what the outcome of his going would do. Right now, you need to work on yourself without him. Your feeling better shouldn't revolve around how he feels and what he's doing.
I hope you'll start just worrying about yourself as a person. You can stop your pain by yourself. Don't go beating your head up against a wall. It hurts to ask and have him tell you he won't go, so don't ask or expect it.