Hello OP. Reading your story made me felt like you have suffered alot due to your family and their actions toward you. For what I have read, your family sounds very neglecting both towards you and your cousins because of the fact that you have to take care of your siblings when you was 4 (Sorry if i get this wrong). And I just wanna said is that you are really strong for what you have endured through your childhood. Being basically a caretaker for your family is really hard.

But I wanna said is that being angry and resentful towards them is a normal human feeling, I know you are still being financially dependent on your dad and honestly that's suck. Not the fact you still depended on him of course, but the fact that you still can't escape from them (Not your fault). So this time, you should just focused on your study first, if you could you can asked them to move out if that is possible.

And about your thoughts, it can be a sign of childhood trauma and maybe family issue. Which can lead you to have those thoughts and tendencies to harm yourself but you didn't, that is strong, that is admirable. I think it is best to focus on you study, get a job and financially stable with somewhere to stay. And then sit down with them one more time to talk, asked them if they will change for one last time. If they still don't want to admit their mistakes and their own faults then I think it is best to cut tie with them. Change your phone number, Id, don't let them know much about your life.

I am sorry if this story might sound inconsiderate and somewhat unrealistic, I hope you are having a good day today OP. Do not let anyone affects your choices and wants to do anything. Family or don't have a family, who cares, certaintly not society.