You have mental blocks with the people.That's why you lose your temper. Try EMDR Therapy for desensitization.They can erase negative feelings about stuttering and people. Being judged, humiliated, underestimated, blamed and pitied. You can also increase your balance against stress. See my M Test definition.If you make it less than 20 Seconds, you will get panic very easily. I achieved from 14 to 50 seconds in 2 years owing to my self developed metod. I became desensitive automatically, since the mind found its own balance.