Hey, sorry to hear that. Group presentations are so much worse. My advice would be to ask for the starting part of the presentation so you don‘t have To stand there while your stress builds up. Additionally I always like to start my presentations too early, so instead of waiting for everyone to sit down, I simply start talking. Doing this I can choose not only the words but the moments I start speaking. After a few sentences I‘m usually fine. Additionally it always helps to give your professor and your group a heads up. Hope that helps and good luck.