My Life in the Fish Tank by Barbara Dee

 

Just before leaving for college, twelve-year-old Zinnia Manning’s older brother Gabriel  takes Zinnia out for ice cream. They pig out on an insane amount of ice cream and then Gabe seems to go crazy on the drive home. Zinny is frightened, and then the family learns that he has crashed his college roommate's car and is being sent home with a mental illness diagnosis. The family is turned upside down and Mom and Dad want Zinny, her older sister, Scarlett, and her younger brother, Aiden, to keep Gabriel’s condition “private.” Soon Zinny's life is dominated by the secrets she keeps from her two best friends, and her science teacher, Ms. Molina. A well-meaning guidance counselor invites her to a Lunch Club with a weird mix of kids who Zinny doesn't believe she has anything in common with. As the year progresses, the family attempts to reconnect with Gabe and each other and Zinny learns who she can trust and who she can't.