The Other Sister by Sarah Zettel- Used

Two sisters. One murder plan.
Everyone thought reckless, troubled Geraldine Monroe was the bad sister -- especially when she fled town after her mother's death twenty-five years ago.
But people don't know the truth.
Marie Monroe knows. She was there for their father's cruel punishments, the constant manipulation, the lies. Everyone thinks she's the perfect daughter -- patient and kind, and above all obedient. No one would suspect her of anything. Especially not murder.
Now Geraldine's home again, and she and Marie have united in a plan for the ultimate revenge. But when old secrets and new fears clash, everyone is pushed to the breaking point . . . and the sisters will learn that they can't trust anyone-not even each other.