When you don't want to be in a situation, you leave. It's really that simple. Do you think you're doing him a favor by staying? Trust me, you're not. It sounds like the relationship has been over for a awhile. Alanon is a huge help because we learn to deal with our own issues instead of keeping the focus on someone else. If the "why me" thinking comes up I suggest understanding that no one put a gun to your head to force you to stay with him.