Stress and an exam tomorrow :(

Hey, first of all, thanks for reading this post because it's quite long. I wouldn't usually talk about my problems but I'm starting to feel so stressed I'm about to burst so here goes:

I'm lying in bed and I have an exam tomorrow at 9.30 which I've just not been able to prepare for AT ALL and I really am starting to worry I will fail. I've had a lot going on lately and I feel like my head just couldn't cope with all of the concentration of revising because I've not had a break in so long basically I've had assignments over Christmas which I was working so hard on all the holidays, and when I'm at home I spend a lot of time helping my mum care for my brother who is terminally ill with mental health issues. It really takes a toll on me because I live 5 hours from home and I usually find the transition between uni and home quite difficult. At the beginning of December one of my coursemates died which was so difficult in itself and I'm still coping with that in some ways, and my other brother is also separating with his wife who I'm really close with. Last semester I was getting some treatment from a uni mental health practitioner for OCD although we're only allowed to have a certain amount of sessions before it runs out. I've got a doctors appointment this week but it will be the first time I've seen a doctor; I think I thought I could cope with everything but with each day I'm feeling more and more alone and all of this stress is finally catching up with me. I don't know what to do if there is even anything.. I guess I'm just typing it out here because none of my friends know about my stressful homelife and the only person I've ever told is my boyfriend, but I feel like it's unfair of me to keep leaning on him and at the moment I'm crying everyday with stress...I just don't know what to do

Thanks for reading anyway,I tried to keep it as concise as possible x