I know exactly what you are talking about. I've been fairly fluent these past 3ish years and I had this moment happen to my last Saturday when I had to ask for a to-go box. Ngl I was embarrassed, but I coped with it by understanding that I probably won't see this person again and that I won't let this experience ruin my day. You also gotta celebrate small victories too. If you got out your sentence, even with stuttering involved, that's a W. Because you still overcame the obstacle and continued the convo.