Unfortunately, the only way to reduce fears and threats is by proving to yourself that speaking does not equal fear. As I explained to Sun, right now, your brain has thousands of dysfluent memories, so it thinks SPEAKING = STUTTERING = EMBARRASSING = FEAR TO SPEAK. By using the crutches over and over again, you teach your brain SPEAKING = FLUENCY = CALM = NOT EMBARRASSING = FEAR TO SPEAK UNNECESSARY. Your brain will then stop generating fear when you speak because you have shown it that it is not necessary.
It is kind of like some of the dogs you find at the shelters. When somebody adopts them, it is common to hear about how scared they are of being touched by a human. Why? Because they were probably abused before. So their brain associates touch with pain and therefore the brain generates fear. The human then keeps trying to touch the dog in a warm and loving way and guess what happens? Eventually, the dog starts realizing that touch does NOT equal pain and therefore stops generating fear and the dog even starts to enjoy being touched and cuddled with.
It would not be enough merely to touch the dog once without causing him pain for him to understand that touch does not equal pain, it takes multiple attempts.
In summary, we cannot explain this to our brain, we have to show it through multiple experiences. Does this make any sense?