Queen Mother, Prince Andrew, Prince Edward, Sarah Ferguson, Princess Diana, Prince Charles and Queen Elizabeth II
Queen Mother, Queen Elizabeth II, Prince Andrew, Sarah Ferguson, Lord Linley, Prince Edward, Prince Charles and Princess Diana outside Clarence House on Aug. 4, 1989. Getty Images/Johnny Eggitt

Sarah Ferguson made a huge mistake decades ago that cost her relationship with Queen Elizabeth II. The Duchess of York felt bad for betraying the bond that she has built with Her Majesty ever since she invited her to the Royal Ascot in 1985.

During Prince Andrew and Fergie’s separation, the latter was involved in a major scandal. The mom of two was photographed with the business tycoon, John Bryan, who seemingly sucked her toe while they were hanging out.

Ferguson and Bryan’s controversial photo made frontpage news, and the Queen saw it while having breakfast with Prince Philip in Balmoral. In her book “My Story,” Prince Andrew’s ex-wife admitted that she was very ashamed of what she had done.

“She was my mother-in-law and my Sovereign, and a woman I cared about deeply – and this is how I had thanked her. I had let down a person who had never let me down, the last person in the world I'd have wished to disappoint,” she said.

The Duchess of York went to see the 93-year-old royal at 9:30 a.m. and the Queen was furious at her. Ferguson immediately apologized to her mother-in-law, but she also knew that some mistakes are very hard to forgive.

“I had apologized, of course, but penance and contrition have their limits – there are some things which cannot be put right. Her anger wounded me to the core, the more because I knew it was justified. I had violated her trust. I’d betrayed the bond that we’d built ever since she had invited me to Royal Ascot in 1985, as one of the younger people she enjoyed having about,” Ferguson said.

Shortly after the confrontation, the Queen and Ferguson had a falling out. But their relationship has improved in recent years. In fact, even after the Duke and Duchess of York’s divorce, Her Majesty continued to invite Princess Beatrice and Princess Eugenie into her home.