I don't know you. But if I were to guess, the anxiety over what they think of you is worse than if you just knew they think you stutter or are dumb. So remove the anxiety. Just accept that they think you are dumb, and work within that dynamic. As an analogy. Balding sucks, but being bald isn't so bad. Once I started shaving my head, it was so much easier to deal with being bald.