Moving past embarrassment and mental blocks?

Moving past embarrassment and mental blocks? So for context, I have a block stutter and it just shows up whenever it wants, but I mostly stutter in nervous situations or when I think that I’m gonna stutter. for instance, in my head before I’m about to order, I just run through the sentence and if the scenario me stutters I usually end up stuttering. I get stuck on mainly words that require my mouth to close (B, M, etc) and also W for some reason. I do highly believe that the scenario thing is mental and makes me stutter even more. But anyways usually I have no problem with just stuttering and then moving on with my day but I stuttered in front on this server like 2 days ago on the word banana. I couldn’t get the word out, ended up telling him I have a stutter and apologizing before letting the guy behind me go and taking a sec to calm down. Eventually was able to order and say banana. He was super nice about it and told me not to worry. But I went back to the store yesterday and he’s there and I just can’t help but feel embarrassed like “what if I stutter again because it’s the same guy and the same order” I think I ended up going back outside and just didn’t order anything. I’m currently kicking myself in the face for it tho bc I know that was such a cowardly move on my part and I’ll probably develop even more of a mental block. But I just can’t help feeling embarrassed. How do I get past this mental block and stop the scenarios of my stuttering in my head right before I talk??