Oprah Winfrey revealed on her talk show Monday that she has a half-sister named Patricia that she never knew existed, calling it a “bombshell family secret that left me speechless.” Holding back tears, Winfrey acknowledged that “I thought nothing could surprise me anymore, but let me tell you, I was wrong.”

Patricia, whose last name was not given, is nearly 10 years younger than Winfrey, who learned of the news just before Thanksgiving, saying it “literally shook me to my core.”

An emotional Winfrey explained that she broke the news on her talk show because “there is no way, with how the media works today, that a story like this wouldn’t get out in the press and wouldn’t be exploited. I didn’t want that to happen, because it’s true. If it wasn’t true, I wouldn’t care what the media says. But it is true. And I wanted you to hear it from me first.”

Oprah spent much of the Monday program detailing how her half-sister realized she was related to Winfrey and the long process of how they finally made contact and the reaction of her mother and sister when they met in Milwaukee, which was recorded on home video. Oprah thanked her sister for not going to the media with this news.

Winfrey was born to unwed teens and was raised at various times by her grandmother, mother and father and stepmother in Mississippi, Wisconsin and Tennessee.

She got pregnant at age 14, but her baby died a short time later. Earlier this week on Piers Morgan's CNN show, she said she wouldn't be where she is today if she had had the baby.