A level Chemistry exam tomorrow. Just want to kill myself.

I have my A level chemistry exam tomorrow and I'm not going to get my A. I was supposed to go on and be a doctor and now that's not going to happen I just don't see the point. Now it's getting late and I'm desperately trying to revise with my mum blasting love island at full blast from the living room next door. I get no support and yet she'll hate me when I fail. How do I keep going knowing that I'm not good enough?