I think school/college is the most damning years for stutters. Kids are assholes, period. They WILL make fun of you to show off in class/be humorous/be cool in front of their friends/etc. The sensitivity towards such issue is non-existent at that age. So the fear of speaking up in public sets in from that age, when you are constantly in fear that any random asshole will show up from nowhere and make fun of you. That mindset sticks through out your adult years and does irreparable damage. At least, that's what happened to me. I was constantly bullied for my stutter and weight, and now I am always conscious of myself in public despite losing much of the weight, or speaking up to strangers because even though they are adults and possibly won't make fun of me...but what if they do? I have seen grown adult smirking or laughing at my stutter. Anyways, OP, fuck that person. Don't let it get to you, however hard it may seem to be. Combat negative thoughts. Fight that person if you have to. Fuck it. Don't let it damage you.