Sweetie, I'm so sorry about your loss. The reason your folks are acting the way they are is because they're grieving. They loved your sister dearly, just like they love you dearly, and they probably are blaming themselves for her death. You're right when you say that your mom shouldn't have gone back to work so soon after your sister's death. But I think that she probably was trying to use work as an escape from her thoughts and her grief, which were and still are overwhelming. I'm also not surprised that your parents appear to have forgotten that they have another child, namely, you. They're so overwhelmed with grief and guilt right now that they aren't thinking straight.
You need to do whatever you can to get yourself and your parents into some grief counseling. Start by reaching out to someone at school, like the guidance counselor, or the psychologist if your school has one. Or tell a teacher you trust. Whomever you tell is your choice, but remember that you CAN'T keep silent about something like this. You and your family NEED HELP, and the only way that you can get it is by speaking up and letting other people know what's going on at home. Professionals like teachers and school administrators are trained to help students deal with losses and tragedies like this.
You may think that your parents aren't interested in helping you with college, but I think otherwise. I think that once they get over the shock and the grief from your sister's death, they may very well pin all their hopes an dreams on you, and will likely do whatever it takes to see that you get a good education. Of course it doesn't seem like that now, because they're still actively grieving the loss, and so are you. But when things calm down and the three of you finally start to feel better, their viewpoint will change. That's why, even though it's tough to concentrate and do your schoolwork right now, you need to keep your grades up and stay involved with school and life. You have an important job to do, which is to get accepted into a good college. Your folks WILL come around at some point, and they will help you.
· 4 months ago