I recommend toastmasters! Along with CBT, look up somatic therapy. While CBT helps you change your mindset and how you handle external situations, somatic therapy focuses on how your body has been trained to react to certain stimuli /trauma, i.e. stuttering. Somatic therapy will help "reprogram" your body's responses. Both can be very helpful, but have different functions. Also keep in mind, you have been dealing with trauma for decades, it can take a very long time to effectively deal with it.