Oprah Winfrey by Stephen Lovekin/WireImage.com
said in a press conference in Chicago yesterday that the alleged abuse at her multimillion-dollar academy for girls in South Africa "was perhaps the most devastating moment of my life. It has shaken me to my core." Former dormitory matron Virginia Mokgobo was arrested last week on charges that included verbal, physical and sexual assault against the students in her care. Winfrey, who said she cried for a half hour when she first heard the allegations, has dismissed the head mistress and given each girl at the school a cell phone programmed with her own phone number. But despite the recent problems at the academy, Winfrey says, "I don' think that as a school we have failed the girls. There are systems within the school that failed the girls." The media queen turned philanthropist went on to say, "I don't feel that it has harmed my personal reputation because I have done nothing wrong."