The fear,anxiety,humiliation and embarrassment caused by stuttering can be crippling. Only someone with stutter can understand your pain. What helped me deal with fear and anxiety was starting meditating and reading books about spirituality. Look up Echkart Tolle his book « the power of now » really helped me understand the source of anxiety and fear and to move away from them. You can find many of his videos on youtube and books on audible. Also learning to breathe deeply diaphragmatic breathing helps to relax the muscles and lessens anxiety.