Kate Middleton was “mortified’’ over loose-lipped sister-in-law Meghan Markle’s claim that the Duchess of Cambridge made her cry — and it’s not even clear that is exactly what happened, a royal expert says.

Markle asserted during her explosive TV sit-down with Oprah Winfrey last week that Middleton reduced her to tears over the flower-girl dresses Markle chose for her 2018 wedding to Prince Harry.

Middleton was horrified that Markle publicly said she made her cry because Kate “has never wanted any suggestion of a rift with Meghan to come out in the press,’’ royals author Katie Nicholl told OK! magazine.

“Kate is so discreet and respects her personal life. You never hear about her falling out with anyone because she is very careful with how she treats others,” Nicholl said.

“So for this story to be circulating is very hard.

“Kate felt [the incident] was all sorted, so to have it brought up again was mortifying.’’

Making matters worse, Meghan and Harry know Middleton is “not in a position to respond” to the claim — which has not been publicly verified by anyone else, the Buckingham Palace expert added.

Kate Middleton visits School 21 in Stratford on March 11, 2021, in London, England.Justin Tallis – WPA Pool/Getty Images

“From what I hear, there are different versions of the bridesmaid story, not just the one Meghan discussed,” Nicholl said.

Markle claimed to Oprah that while stories in the press painted her as the villain at the time, saying she made Middleton cry, the “reverse” happened.

The two duchesses had a tiff about Markle’s flower-girl dresses, “and it made me cry, and it really hurt my feelings,” Meghan said.

“It was a really hard week of the wedding and [Middleton] was upset about something, but she owned it, and she apologized, and she brought me flowers and a note,” Markle added.

The Duchess of Sus𝓈ℯ𝓍 and hubby Harry went on to drop other bombshells, including that an unnamed royal made a racist comment to the prince asking how dark their son Archie’s skin would be, given that Markle’s mother is black.

Harry also claimed his brother, Kate’s husband Prince William, their father, Prince Charles, and grandmother Queen Elizabeth II are all “trapped” by their royal life and that his relationships with his sibling and dad are troubled.

Nicholl said that behind closed doors, Middleton “has been saddened, disappointed and hurt” by the couple’s comments.

Princess Charlotte, Kate Middleton, Jessica Mulroney, Ivy Mulroney, Florence van Cutsem, Zoe Warren, Zalie Warren, Benita Litt, Remy Litt and Rylan Litt arrive for the wedding ceremony of Prince Harry and Meghan Markle at St George’s Chapel, Windsor Castle on May 19, 2018.Ben Stansall – WPA Pool/Getty Images

“Kate and William feel they were hugely welcoming to Meghan and Harry. Any accusations against the monarchy are accusations against their family. It’s hurtful and they feel let down,” the expert said. “Obviously, they still love Harry and Meghan, but this interview has ruffled feathers.

“William is beyond livid with his brother,” Nicholl added. “He, Charles and the Queen held crisis talks in the days following the interview on how to proceed.

Princess Charlotte and Kate Middleton on the day of Harry and Meghan’s wedding on May 19, 2018.Jane Barlow – WPA Pool/Getty Images

“It’s well documented that the brothers were making steps to reconcile their once-close bond, but sources claimed William felt the Oprah interview was the final straw.”

Still, “despite the anger, they both want to resolve this feud,” she said.