For me, my fixing, saving and rescuing attempts gave me some sort of self worth. It was also a distraction from looking at myself. I really had no idea I was even doing this until I started learning about codependency.
When I needed to say NO, I would often become angry at that person because I was left feeling guilty. The anger masked my guilty feelings. Although, I find it much easier to say NO, I still struggle with the feelings of guilt but I have let go that anger. I find giving my "unhealthy guilt" over to God is the only thing I can do at this time.
You are showing great insight. Have you read Codependent No more yet?? It was a huge eye opener for me.