Just try to relax. In your head your building this up to be a huge a event but it’s just a 10 second introduction. Maybe email the professor and explain your situation, people are very understanding if you just explain yourself. Maybe she/he could skip you or you could miss that first class. This curse we live with is terrible and can really put us in a dark place but I’m sure there is a lot of good in your life so try not to focus on your stutter, you are more than your stutter. I assume you’re out of high school now and people are much more accepting of stutters. Like I said just contact the professor and I’m sure you can come up with a solution. Or you could do like the others said and practice. Either way I’m sure it will be just fine, just try not to stress too much about it.