Don't get humiliated, get angry at them - that is utterly unacceptable, and if you have any route to report them, you really should. I had "if you can't speak properly don't speak at all" from one of my parents and I'm still trying to shake that off - with help from an excellent speech therapist, who's helping me get to where it sounds like you already were i.e. "I have no issues related to presenting, I stutter but I don’t mind". That's an amazing place to be - don't let this absolute awful idiot affect that, please.