Prince William & Kate Middleton Have 'Major Concerns' Over Prince Harry's Royal Memoir, Assume He'll Write About 'How He Suffered Growing Up'

Prince Harry has promised to tell it like it is in his forthcoming memoir, which is due out by the end of 2022.

“[It will be a] firsthand account of my life that’s accurate and wholly truthful,” he’s said of the tell-all.

According to a source, royal family members — including the Queen and Harry’s estranged brother Prince William and wife Duchess Kate — have “major concerns” over what Harry will reveal.

“No one expects him to hold back,” says the source, noting that the tome is part of a $20 million deal with Penguin Random House for four titles. “They assume he’ll write about why he left the monarchy, how he suffered growing up, how the family handled the death of his mother, Princess Diana, and his conflicts with his father, Prince Charles.”

PRINCE HARRY IS UNLIKELY TO ATTEND PRINCE PHILIP'S MEMORIAL SERVICE: IT WILL 'UNDERMINE HIS POSITION THAT IT'S TOO MUCH OF A THREAT' AS SECURITY APPEAL CASE BEGINS, SOURCE CLAIMS

The book threatens to drive an even bigger wedge between Harry and his family. “Charles and William have both made some terse comments to Harry about the memoir, but Harry’s staying mum about its contents,” adds the source. “Writing has been cathartic for him, and he hopes it will help others.”

As OK! previously reported, despite Harry's brother and father not fully supporting his writing endeavors, cousins Princess Eugenie and Princess Beatrice fully have his back as he steps into his role as an author.

QUEEN ELIZABETH II CONTRACTING COVID-19 IS A 'HUGELY WORRISOME SCENARIO' FOR THE ROYALS: 'EVERYONE IS HOLDING THEIR BREATH THAT SHE'LL COME THROUGH THIS SAFELY'

"They believe Harry's outspoken remarks may have been triggered because previously his voice and opinions were rarely heard within the royal family," a source told Vanity Fair of his cousins' support, adding that the royal sisters believe Harry "is finally being listened to."

The Duke of Sussex and Duchess Meghan Markle were recently seen dining out with Eugenie and her husband, Jack Brooksbank, in Santa Barbara while the princess and her spouse enjoyed a break from British life in California.