She brought it all on herself!
Lily was the one playing mind games with the art professor and seducing him. She even let him kiss her and almost go down on her. What does she expect? He's a man whose cheated on his wife before and obviously he preys on young woman but she didn't care. She didn't care if having an immoral relationship with the professor hurt his wife or daughter because she was stupid and selfish. Does she expect there to be no consequences. She's also the bipolar slut who had a boyfriend and goes to a party and decides to kiss another guy right in front of him to make him jealous. I can see why it's called Poison Ivy because she's not so innocent and can cause a lot of trouble wherever she goes!