Daughter of Chaos (The Chilling Adventures of Sabrina Novel 2) By Sarah Rees Brennan

Sabrina Spellman has just made the hardest decision of her life: she's leaving behind her beloved friends at Baxter High. Now it's time to follow the path of night and find her way among the witches and warlocks at the Academy of Unseen Arts. Sabrina has always been good at the school thing, but now she has a whole new world to navigate. Her power is growing daily, but it comes with a high price. She must always remember her new allegiances and the cost they have on her friends and on herself. And then there's her new classmates. Prudence, Dorcas and Agatha are friends, kind of, but can Sabrina trust them? And what about Nick Scratch? He's as charming as ever, but will his feelings for Sabrina last?