I think the first and huge step to do is acceptance, not as something that will last forever but like some kind weak side to work on and improve, everyone has these bigger, lesser, noticeable not noticeable and so on. You should focus more on yourself instead of how do you seem to others how they feel about you talking, start not giving a fuck about what others thinks. Show them how well you can stutter, stutter on purpose sometimes, ive experienced that blocks dont come up when i fake a slight stutter, try to keep eye contact too. Breathing/relaxing exercises help too. I think a good way of facing these thoughts is to jump in situations that you feel you could never manage to speak well, try on these over and over, ive learned that improving my confidence by doing this and forcing myself to not pay attention to what others think its helping me. I don't know if i went on the point well, hope something can help