Girl A by Abigail Dean

Lex Gracie doesn't want to think about her family. She doesn't want to think about growing up in her parents' House of Horrors. And she doesn't want to think about her identity as Girl A: the girl who escaped, the eldest sister who freed her older brother and four younger siblings. It's been easy enough to avoid her parents--her father never made it out of the House of Horrors he created, and her mother spent the rest of her life behind bars. But when her mother dies in prison and leaves Lex and her siblings the family home, she can't run from her past any longer. Together with her sister, Evie, Lex intends to turn the House of Horrors into a force for good. But first she must come to terms with her siblings - and with the childhood they shared.