Welcome to F&F, CocoonGirl. I have a hunch that you're in the right place. Have you had a chance to read the stickies at the top of the board? You might also pick up Codependent No More by Melody Beattie. Even if you're not currently in a relationship with an addict, you'll learn so much by studying the patterns that us codependents rely on just to deal with life.
OK, I could be wrong, but you seem like a person who is awfully hard on herself. I picked up on this because you sort of cyber-flinched when people asked you for more detail about your previous relationship. Nobody even suggested you're in the wrong place--that came from you. We simply asked for more information--a neutral question.
This is not a criticism of you! One of the patterns of codependency is to assume we're wrong and other people are right. Some of us even believe we're wrong just for existing and having needs. We're sensitive, caring people and are easily hurt, and for some reason (it's our job to find out why) we choose the people most likely to hurt us as partners.
As I read your description of your therapist's interactions with you, I wonder if the "doing it wrong" reaction came from you internally, rather than from her. Maybe it didn't--maybe she was just an incompetent therapist (only an incompetent therapist would tell you you did an exercise "wrong.") But part of the healing process for codependency is untangling that huge snarled ball of yarn that is our emotions and separating what's coming from inside us from what's coming from other people. Did she actually say, "you did it wrong?"
Just some food for thought. I hope you stick around and find peace and self-love from what you learn here. I know I have.