Ellen DeGeneres may be known for her sunny disposition as one of the TV's most famous talk show hosts, but she has revealed a painful memory from her past in a new interview.

The 61-year-old is a guest on the forthcoming second season David Letterman's 'My Next Guest Needs No Introduction' Netflix interview series. In it, she spoke about being sexually assaulted by her stepfather when she was 15.

Rather harrowingly, she said that he used her mother's breast cancer diagnosis to manipulate her. "He told me when she was out of town that he’d felt a lump in her breast and needed to feel my breasts because he didn’t want to upset her, but he needed to feel mine,” she told Letterman. "He convinced me that he needs to feel my breasts and then he tries to do it again another time, and then another time.”

She added that she had been angry at herself for being "too weak to stand up", but said that she was sharing her story to empower other young women. "It’s a really horrible, horrible story and the only reason I’m actually going to go into detail about it is because I want other girls to not ever let someone do that,” she said. "We [women] just don’t feel like we’re worthy, or we’re scared to have a voice, and we’re scared to say no. That’s the only reason I think it’s important to talk about it because there’s so many young girls and it doesn’t matter how old you are."

The series - which also features Kanye West, Tiffany Haddish and Melinda Gates - debuts on Netflix this Friday, May 31st. Watch the trailer below: