I haven't revised for my exam tomorrow, and I'm panicking not sure what to do

I've got my maths a-level exam tomorrow (edexcel) but I have not revised for it yet, I've been trying to start but I just have an overwhelming sense of panic that I just can't put down because I know I'm going to fail since I'm just so clueless.

I know I'm a complete idiot, and I'm so so screwed. I'm trying my best to revise now but it's far too late. I'm so sorry for imposing my problems on to you guys but I'm honestly having suicidal/depressing thoughts about it since I will not be able to retake the exam again.

I just don't know what to do.

I can't resit it anymore, it's just not possible.

Why not?

Because I've already done it once, doing it again is physically not possible.

I can't resit it anymore, it's just not possible.

I'm trying to go through the entire textbook, but there's just so much and it's so overwhelming. It's gotten to the point where I look at past papers and I look at the question and just realise, that I'm so, so done for.

I think I broke down for 10 minutes and started questioning my entire existence and what I been doing with my life until now. It's like you know your own death is coming but there's nothing you can do but sit through it. I dread everything about tomorrow, the exam, the hall, the people, post-exam.

I'm wallowing in self-pity right now, but it's the only thing that I seem to be able to do right.