It depends on the situation. Are they ignorant of your speech impediment? Do they not understand? Are they being mean? If you're unsure, give them the benefit of the doubt. Regardless, assume control. You're in no way obligated to answer someone on their terms. Or on their timeline. You are your own master. Something as simple as "I'm really trying" or "I stutter" can often bridge the gap. If they're being mean, stare their ass down. Turn and walk away. Take the control back. All of this is easier said than done. Don't dwell on these events. It happened, get over it. Maybe assess how you would have handled it better. Know that next time it won't be the same circumstance. But don't let it rattle around in your head. That's harmful. We do our best. Look forward.