I don't know how to react after this experience (Half rant, half advice)

I don't know how to react after this experience (Half rant, half advice) I (26 m) have mild stuttering (which can easily go up to moderate in certain settings). Today I was feeling quite happy and confident, so I decided to go for a cocktail before heading back home. I sat at the bar and the bartender brought the menu, but I already knew what I was going to get, so I told him "Can I have a champagne colada please?". But... I stuttered a bit (1 to 1.5 seconds long) while saying "champagne". I didn't mind stuttering at all while saying it, but what happened afterwards took me by surprise. The bartender mimicked my stuttering in an exaggerated way and said "Yeah you can have a ch-ch-ch-ch-champagne colada.", grinning. I immediately said "I think I won't.", stood up, and left the place. One of the customers at the bar said "Noo, it was a joke.", which I ignored. After I left the place, the bartender followed me, and started apologising. I told him "I have a speech disorder and you're making fun of it. That's really not okay." and he kept apologising. I said "Just leave me be, I'm used to it anyway.", and then he said he thought it was my way of joking, and that he thought I was just joking. For reference, I lose control of my muscles when I stutter, and the twitching is visible, although not major or full-body. Because of that, I doubt he only came up with an excuse. Afterwards, he was talking about making it up for me even while I was walking away. He said the first three drinks are on him and whatnot. To be honest, it was obvious that he was genuinely sorry, and I appreciate that he was doing the right thing by doing his best to save the situation. However, I found myself having to pinkie promise that I'll be back some other time and reassuring that it is okay, to the point that I felt like I was consoling him. I was thinking about multiple things: 1- I just wanted to escape from the uncomfortable situation, 2- I didn't want to have an awkward conversation with the guy, 3- I didn't want to see the other people at the bar, especially the customer who said "It was a joke", 4- I thought if I accepted a free drink, then it would have meant that being ridiculed is purchasable with the price of a cocktail (although I logically don't think that was the case here, and that he was genuinely trying to make up for it). After consoling him enough and promising to come back, I went back home and tried not to cry. Maybe it's because I was lucky enough to not be bullied too often and that I'm living in a fairly developed country in Europe that I was this shocked. Any advices, thoughts, similar experiences etc. are welcome.