For caring ppl help me in this problem please.....i really need hlp?

Untell recently my Aunt Died with Brain Canser.[that she had it in 2004]..she live's in Callifornia and I haven't seen her for like 10 years ..but as i remember her she was really great and loving...my whole family felt so sad about her especially my Mother [they were bestfriends]..its bin a month and my mother dont talk or take care to anyone..i am the bigges in the family and my Dad dont live with us so its my responsabilty to do her job...i am 18 years old and i have 3 brothers the ages between 5 and 12..i have my SAT exams in the 3d June and i didnt study anything yet....its not fair we all felt sad but i need to p this exam so i can go to collage...i told my mother several times but she actually didnt answer...and i cany left my 3 brothers ....please what should i do