My enemy became my stepsister

Leela is a shy, creative geek.
Taylor is her enemy, popular, pretty and she won't stop bullying Leela.
Olivia is stuck in the middle, she's Leela's best friend, Taylor wants to be her friend and she's so kind she doesn't want to be mean to even her best friends enemy.
Leela's mother died when she was a baby.
Taylor's father left her and her mother when Taylor was five.
One day their parents meet and Leela's worst nightmare happens.