Self- confidence – thoughts versus allowing difficult feelings

I am grappling with an aspect of the concept of self-confidence. Self-confidence, according to LCS teaching, involves (besides keeping to your word and your opinion of yourself) the willingness to feel any feeling that comes up. So, let’s say I want to give a speech, and I am feeling anxious about it, because I am worried that I’ll feel so anxious I won’t be able to speak competently, and need to leave the stage. I would feel humiliated because my thought would be “I have failed in front of 100 people.” This would be my model:
C Speech, I can’t talk, I leave the stage
T I have failed in front of 100 people
F Humiliation
A Curl up in a ball and hide
R I fail myself – I don’t attempt going back on stage, and I judge myself/don’t have my own back

So if I am willing to feel humiliated, I will feel self-confident?
But how would I feel humiliated, if humiliation comes from my thoughts? All I need to do is choose a different thought, e.g. “coming off stage doesn’t mean anything about me as a human being. I’m still valuable, competent and worthy.”

C Speech, can’t talk, leave the stage.
T Failure means nothing about me as a person. I am valuable competent and worthy
F Confident
A Go back up on stage?
R Give the speech?

Or am I not doing the right models, it’s more about anticipatory models?
C Been invited to give a speech in front of 100 people
T It’s possible I can’t speak and leave the stage but I can handle any feeling
F Self-confident
A Practice the speech
R Give the speech competently

My question really is – if I truly, 100% believed that I could give my speech with no problems, I wouldn’t even need to allow any uncomfortable feeling. I could just deliver a great speech by thinking I will. So is the fact we have to be willing to experience any negative emotions because sometimes we don’t really believe our more helpful thoughts?