Paris Hilton is ready to publicly address a difficult part of her past. In a new sneak peek at her upcoming YouTube Originals documentary "This Is Paris," out Sept. 14, the heiress says she is still haunted by a painful childhood memory she kept under wraps until now. According to People, the 39-year-old suffered mental abuse while attending boarding school in Utah as a teenager and she discussed the situation on camera while shooting her new project over the course of a year. In the clip, Paris confesses that she hadn't shared the troubling incident with anyone before and was so nervous she was shaking and unable to eat, admitting the experience has lingering effects today. "No one really knows who I am. Something happened in my childhood that I've never talked about with anyone. I still have nightmares about it," Paris said.