Hi Adamk01, and welcome to PC. I'm sorry for your physical and family problems. Surely they doesn't helpyou concentrating on study. But if you failed the exam I think that it could also be because you didn't sleep enough and only studied. You also need rest to can concentrate and remember things. I'd suggest that you try to take more pauses during study.
About your brother, probably he needs psychological help. Could you suggest it to your parents, if you are afraid to talk to him? If you live with him, maybe it would be better to go to stay in college or to take an apartment with some friends, so you could feel more relaxed and safe.
Wish you all the best