Prince William was “literally sick with worry” leading up to Prince Harry and Meghan Markle’s explosive March 2021 sitdown with Oprah Winfrey.

In the latest Kate Middleton biography, “Kate! The Courage, Grace and Power of the Woman Who Will Be Queen,” author Christopher Andersen claimed the Princess of Wales “could hear her husband retching in the bathroom” for a full week before the interview aired.

William, 43, was allegedly “too distracted to think of food” over what his brother and sister-in-law would divulge to viewers.

Page Six has reached out to William’s rep, who did not have a comment.

The couple’s conversation with Winfrey, 72, touched on many subjects, including Middleton’s argument with Markle over Princess Charlotte’s flower girl dress days before the latter’s May 2018 wedding, which left the bride, 44, in tears.

Harry, 41, also confirmed he was not on good terms with William, saying there was “a lot of hurt” between the estranged siblings.

Perhaps the biggest bombshell was when the “Suits” alum called out unnamed members of the royal family allegedly raising “concerns” with her husband over their unborn child’s skin color and “what that mean[t]” for the monarchy.

The Duke and Duchess of Sussex’s first child, Prince Archie, was born in May 2019, followed by Princess Lilibet in June 2021.

King Charles III is believed to have made the remark on Nov. 27, 2017 — the same morning Harry and Markle’s engagement was announced.

According to Andersen’s 2021 book, “Brothers And Wives: Inside The Private Lives of William, Kate, Harry and Meghan,” the now-monarch mused to his wife, Queen Camilla, “I wonder what the children will look like? … I mean, what do you think their children’s complexion might be?”

A spokesperson for the 77-year-old has since strongly denied the story.

Unusually, Buckingham Palace drafted a statement about the Winfrey interview, which took place during Queen Elizabeth II’s reign, and the response was shown to William and Middleton.

Andersen wrote in his Middleton biography, out Tuesday, that the first draft did not mention the charges of racism — but the princess, 44, insisted those be included.

The biographer alleged these sentences were subsequently added: “The issues raised, particularly that of race, are concerning. They are taken very seriously and will be addressed by the family privately.”

Andersen noted that while “William was about to sign off on this version,” his wife “wasn’t satisfied” and brainstormed another change.

“It was at this point that Kate suggested the phrase ‘while some recollections may vary’ — making it clear that not everyone was on board with what Harry and Meghan were saying,” Anderson wrote.

Harry and Markle were “not surprised” by that phrasing, Omid Scobie and Carolyn Durand claimed in “Finding Freedom” in August 2021.

The comment taking “little accountability” reportedly “did not go unnoticed” by the ex-royals, who have lived in Montecito, California, since 2020.