I had a group presentation 2 days back. I couldn't finish it and i stuttered severely throughout. But im happy i got through it. I have missed some group presentations calling in sick, but i always regretted it . Now the fact that i faced it despite stuttering severely has given me a sense of accomplishment. I think you should just go and face it even if you can't say a single word. The higher ur fear goes, the worse ur stuttering will become. So just do it. All the best !!😄