I've been there. I know you can't will yourself to not care. But you can will yourself to throw yourself into those hard situations. It's not easy but you need to build up that scar tissue. Stuttering is harmless, physically. Stuttering is a blessing in my opinion, not a curse. It makes you unique. You stand out from the competition. I've found this an advantage both professionally and in relationships. The only good advice I can give is let yourself get beat up, embarrassed, etc from stuttering, just keep putting yourself out there and weathering the storm. Eventually it gets easier, and you get numb to any embarrassment. But it will always hurt if you hide from it. Need to build up that scar tissue.