Please do not misunderstand what I'm about to say next--I'm coming from a good place and I'm only saying this because I really do not want you to go through the same situation ever again. I am not sure how supportive your school environment is in general, but reading your post makes me wonder if you have reached out to your professors explaining your stutter and past near traumatic experience when you had to give a presentation and ask them if you could submit some other work instead of giving a presentation.. From my experience, most professors have taught students who stutter in the past and many are informed of how detrimental the experience of public speaking can be to them. Idk... I feel like a big part of our problems in life can be resolved or at least dramatically reduced via good communication skills (whether it be verbal or written!). Not sure if it's too late but I strongly encourage you to email them even now explaining your situation and see what they have to say!! If it's too late to change grades for this semester, please keep this in mind and actively communicate with your professors for the rest of your time at college. I think we tend to underestimate the level of support in our social networks--most people are willing to help and work things around if you ask!