I need to think more about this but something I can add right now.

I had a T once who always said, "what are the facts" when you have negative self-talk and name calling. I can clearly see by your post, you are not stupid; you were clear, concise, and actually argued your way out of being stupid. Taking a step back to see this for yourself is important.

We all do things we are less than pleased about but it does not make us x, y, z or even stupid. When we label ourselves, we take it in in a harmful way and that in an of itself can erode our self confidence. If you catch yourself doing this, list the reasons (the facts, not feelings) that support why you think it is and then why it isn't the case. More than likely (99% of the time), if honest you will find, it isn't the case. Our brains are really good at tricking us into a repeating type of negative "tape recording" but the thoughts are not grounded in reality; take a step back from it to see what actually IS. Just in doing this, many see positive changes in how they feel, their self-esteem and confidence level.