Disgraced duchess Sarah Ferguson said she spent the day of Prince William's wedding last month berating herself for the past mistakes that left her without an invitation.
Ferguson, the ex-wife of William's uncle, Prince Andrew, told Oprah Winfrey in a U.S. television interview to be broadcast on Wednesday that she did not blame the British royal family for excluding her from the lavish nuptials in London on April 29.
"I think what I felt was that I went through the phase of feeling so totally worthless and that (it) was quite right they didn't invite me. Why would they -- why would they invite me?", Ferguson told Winfrey.
"I felt that I ostracized myself by my behavior, by the past, by living with all the regrets of my mistakes, that I sort of wore a hair shirt and beat myself up most of the day thinking and regretting why did I make such a mistake? Why have I made so many mistakes? So I did spend a good three hours on that," she added, according to advance excerpts.
Ferguson, who still holds the title Duchess of York but lost her status as a princess, was caught in a video-taped sting last year in which she appeared to ask for and accept $40,000 in cash in exchange for access to Prince Andrew.
The 2010 episode followed embarrassing photos in 1992 that showed her topless and having her toes sucked by a Texan businessman.
Ferguson, 51, said she went to Thailand once she knew she would not be invited to Prince William's wedding to Kate Middleton. Her daughters with Prince Andrew -- Princesses Beatrice and Eugenie -- attended the ceremony at London's Westminster Abbey.
The historic church was also the venue for Ferguson's wedding to Prince Andrew in 1986. The couple divorced in 1996.
"It was so difficult. Because I wanted to be there with my girls, and to be getting them dressed and to go as a family. And also it was so hard because the last (royal) bride up that aisle was me," she told Winfrey.
But Ferguson said William's mother, the late Princess Diana, would be proud.
"They did a great job. And I really love the feeling that sort of Diana and I both weren't there. But I'm here to say how proud she would have been and Kate looked utterly beautiful".
Ferguson has made a reality TV series called "Finding Sarah" that will get its debut on June 12 on Winfrey's new cable TV channel OWN.