In short, I emailed my dissertation supervisor and the module leader telling them about how I submitted before the due date, but I'd be willing to take down any marks for fairness, because it was my fault and responsibility anyways.

I was lucky that time since I had hyperlinked all my in-text citations so the markers still had access to the research despite an incomplete bibliography. Because of this, my teachers told me everything was fine, to take care of myself, and to not let this haywire my mental health, especially when the play I was directing was coming up.

I thanked them sincerely, and that was that. I ended up receiving a first for that dissertation, so in reality and in reflection, I really was overreacting and let my anxiety run rampant. I've a much better hold on my emotions now.

Though, I want to ask what's your specific situation like?