Bad Girls with Perfect Faces by Lynn Weingarten

From the New York Times bestselling author of Suicide Notes from Beautiful Girls comes a stylish thriller about the darkness that lurks inside all of us. When I looked up, his smile was wide and real. “Ready?” he said.
I faked a smile back. I had gotten so good at faking things.
I thought: You brought this on yourself, Sasha. You will have to pretend forever now.
He squeezed my hand again. He couldn’t begin to imagine what this actually was. He had no idea what I’d done. What any of us had. When Sasha’s best friend Xavier gets back together with his cheating ex, Ivy, Sasha knows she needs to protect him. So she poses as a guy online to lure Ivy away. But Sasha’s plan goes sickeningly wrong. And she soon learns to be careful of who you pretend to be because you might be surprised by who you become… Told in multiple points of view, Bad Girls with Perfect Faces is sexy and twisted with shocks at every turn.