I’m gonna be a bit different and brutally honest. Do not accept that type of behavior around - especially for speech impediments.You’re too old to tolerate disrespect and need to inform people in a way that if requires not so nice then be it. I have a pretty bad stutter and have had some similar situations. I get that it can be overwhelming and such but anyone who crosses the line - respectfully let them know what’s up and correct their ignorance. It’s time more people know about speech impediments. By letting them sit on the high horse is not the way unfortunately. I hope the best for you.