Approaches to teaching controversial subjects in the classroom - The Perks of Being a Wallflower

Hi everyone! I'm a student at Colorado State University (English Ed and ESL) working on a project about how to best teach controversial subjects. The focus of my project is about the book, The Perks of Being a Wallflower, which is currently the most challenged book in schools. It touches upon suicide, sexual abuse, physical abuse, drug use, alcohol use, straight sex, gay sex, sexual experimentation, depression, etc...
Does anyone have experience in teaching these subjects? Tips? Ideas on how to help parents understand why you are teaching these topics?
Anything would be helpful - thanks for your time!
Laura