Princess Diana and Sarah Ferguson’s close friendship fell apart after the latter published a hurtful claim that she caught “a verruca [wart] from borrowing some shoes from Lady Diana” in her 1996 autobiography, “My Story.”

“In fact, the reality was that Diana was very concerned that Sarah Ferguson might well be selling stories about her, and that relationship was never repaired, though Sarah Ferguson pretended it had,” royal author Andrew Lownie told the Daily Mail in a video published Thursday.

The late princess and Ferguson — who were fourth cousins and childhood friends — were quite close before their falling out. After Diana introduced Ferguson to the former Prince Andrew, the two became sisters-in-law when they married into the royal family.

Diana tied the knot with the then-Prince Charles in 1981 and Ferguson, now 66, followed a few years after, saying “I do” to Andrew, also 66, in 1986.

The pair of women became especially close as they bonded over their shared commiseration of their royal family struggles, Lownie claims.

“Diana would come to Sarah Ferguson every Sunday, and they would moan about the royal family. They both felt very restricted within the confines of the royal family,” he told the outlet.

Lownie continued: “But at the same time, there were some concerns Diana had that Fergie perhaps was too boisterous, and she was kind of undermining Diana’s own reputation, and she began to distance herself.”

Their friendship even allegedly withstood a “tough trick” on Ferguson from Diana, when the two agreed to divorce their husbands at the same time.

However, Diana “let Sarah Ferguson do it on her own and basically learned from how the royal family treated Sarah Ferguson about how she would handle the divorce herself.”

Ferguson separated from Andrew in 1992 after a decade of marriage. They finalized their divorce in 1996, but the pair continued to live together at Royal Lodge — all the way until King Charles III evicted them from the royal property this past February as a final blow after he stripped Andrew of his royal titles last year.

Diana, meanwhile, separated from Charles, now 77, in 1992 and eventually divorced him four years later.

She tragically died at age 36 in a car accident in Paris in 1997.