Oprah Winfrey has called herself a “bigmouth frog” for publicly revealing her engagement to longtime partner Stedman Graham &#151 which has never resulted in marriage.

The 51-year-old star, who has dated Stedman for 19 years, once revealed: “I have the right not to get married. I’m sorry I was such a bigmouth frog about the engagement. That is my biggest public regret.”

Stedman, 54, popped the question in October 1992. The couple contained their secret for a month &#151 but everything changed when Oprah blurted out the news during a local radio interview. Within hours her engagement was being reported by TV stations.

The National Enquirer learned of Oprah’s guilt after being granted an exclusive look at an explosive new book detailing comments made by the star about her personal life.

In The World According to Oprah: An Unauthorized Portrait In Her Own Words, author Ken Lawrence revealed that Oprah blamed herself for the failed engagement.

Interestingly, says the book, Oprah’s attitude toward marriage and having children became more skeptical as her career grew more successful.

Just weeks after getting engaged, Oprah said: “You don’t want to wake up 10 years from now and say, ‘My God, who is this I’ve married?’ So it scares me a little bit.”

Six years later, at 44, Oprah explained why she had not started a family. “Balance? That’s why I don’t have children,” she said.

“People in my audience are always saying they want me to have kids, and I always tell them I have to start this evening because that clock is about to run out.”