@ilybub (probably a way too long response of me, I'm bad at keeping things short)
First of all, letting things out and expressing yourself is always good. I'm really happy you did, it's a step closer to letting others help you and/or helping yourself.
I really want you to know that life is unbelievably special. There are so many things, so many options and so many people who can bother you and hurt you. But you need to get through it. I'm really sorry for the loss of your cousin, yet you need to know, that how it's affecting you now, is how it will affect other people the exact same way if you also give up on fighting.
For now, studying and regular things like that will never be as important as surviving. You need to make yourself the number one of things that are the most important. I genuinely hope you will have a better time, even in your situation.
I'm not a psychiatrist, and so I can't give you the best advice to do what you need to do. But what I do know is that harming yourself is hurtful for later, yet a way out for now. I recommend trying not to make yourself too sick (for example too much blood loss) so your mind/brain can work more properly and help you to think more clearly.
I want you to remember one thing for always: it's okay to feel the way you feel.
(If my message made things worse, please forget about it, I don't want to direct you to the wrong way)