I have been where you are, and I know what it's like to be terrified about getting a B. I went through the better part of my third year in college feeling various shades of suicidal and still managed to finish with a near-4.0 (darn single A-!). It's hard when people don't really see your pain because you're succeeding. But the crushing pressure to succeed just makes the pain worse.

What kinds of support are you getting now? What kinds of support are you interested in? It's tough because students who are struggling often need help with things like tutoring, academic advising, or withdrawing from classes, but I know I wouldn't have been interested in any of that stuff back then. (And frankly it wouldn't have helped my problem.) Do you feel like you're seeing your T often enough? Do you need practical self-care tips to help pour yourself back into the shape of a functional human being? Do you just need a listening ear?

I do think you should consider contacting your professors. It's really common for people to have mental health issues that interfere with school, especially in the fall semester. They might be able to make accommodations for you, and even if they don't, I think there is something inherently freeing about admitting that you're struggling.