I know why I feel like a fraud — why won't it go away?

You did the hard part. You traced this feeling back to where it started — some room, some year, some person who made you doubt yourself. Good. Most people never look that closely at their own mind. But here is what nobody tells you: understanding a pattern does not delete it. You can know exactly why you flinch and still flinch. The feeling will show up in the next meeting whether you've explained it or not. Insight is not the same as freedom. So stop treating the explanation as the finish line. It isn't. The real work starts now — noticing the moment the old story tries to speak for you, and choosing to act as the person doing the work in front of you, not the person that old story described. This is easier to see in others than in yourself. That is why you need people beside you who will name it when you slip back.