IMHO your feelings are totally natural. I've been through a divorce-I know how it feels. It's the worst thing, next to the death of a loved one, you could ever experience. I don't blame you for not wanting to go through it again. But remember how you came out the other side of the first one...you can do it again. Divorce doesn't mean failure. It just means you learned some relationship lessons.
Boy do I know the whole "I cannot stay in this relationship unless there are major changes" -the only one who made major changes was me, and not for the better. I became a mess-which is what a relationship with an alcoholic tends to do.