EXCLUSIVE: Meghan Markle and Prince Harry's bombshell interview with Oprah Winfrey will air in the U.K. Monday evening – and the palace is allegedly already outraged by the tell-all.

In late 2020, British author Tom Quinn released a book titled "Kensington Palace: An Intimate Memoir from Queen Mary to Meghan Markle," where he spoke to those who worked for the royals over the years. During his talks with palace insiders, Quinn learned the Duchess of Sussex, 39, was reportedly nicknamed "Me-Gain" and "the Duchess of Difficult" by palace staff as she struggled behind palace doors.

"People I’ve spoken to say there is a great deal of anger that Meghan didn’t insist the broadcast be delayed until Prince Philip leaves the hospital," Quinn told Fox News.

Quinn shared the palace was also "worried" because they had no doubt the full interview would "reveal the full extent of the feud between Meghan and the royals."

BETHENNY FRANKEL APOLOGIZES TO MEGHAN MARKLE AFTER SEEING EXPLOSIVE OPRAH WINFREY INTERVIEW

During her interview with Oprah Winfrey, Meghan Markle detailed the struggles she endured as a senior member of the British royal family. (AP)

On March 5, days before the interview aired on Sunday in the U.S., Prince Philip was transferred from a special cardiac hospital to a private facility to continue his recovery after a heart procedure. 

According to Buckingham Palace, the 99-year-old husband of Queen Elizabeth II underwent a successful procedure for a pre-existing heart condition at St Bartholomew’s Hospital. He was moved to King Edward VII’s hospital and is "expected to remain in the hospital for continuing treatment for a number of days."

Philip was admitted to the private London hospital on Feb. 16, where he was treated for an infection. 

Several critics in the U.K. pointed out the interview, which aired in the U.S. while Philip remains hospitalized, was poorly timed.

MEGHAN MARKLE, PRINCE HARRY'S INTERVIEW WITH OPRAH WINFREY: 6 BIGGEST BOMBSHELLS

Queen Elizabeth II married Philip on Nov. 20, 1947, at Westminster Abbey in London.  (Chris Jackson/Pool via AP)

Quinn also shared that palace insiders believe the Duchess of Sussex didn’t truly understand what she signed up for when the former American actress married Elizabeth’s grandson, 36, in 2018.

"The palace definitely feels Meghan just doesn’t understand that to be part of the royal family you have to do things the way the royal family does them," he explained. "They don’t compromise. Insiders I’ve spoken to say that Meghan has taken Harry away just as Wallis Simpson took Edward VIII away. People are saying history is repeating itself."

"I think the problem is that Meghan completely misunderstood the royal family," he continued. "They put duty first and would be baffled by the idea that they should have a warm, cuddly discussion when one of their members is upset or experiencing mental difficulties. That kind of thing is just completely alien to the royal family. They believe in the stiff upper lip… The real problem at heart is that there is a vast unbridgeable cultural gap between Meghan and the royal family."

The interview with Winfrey, 67, was the couple’s first since they stepped down from royal duties. Markle acknowledged her naiveté about royal life before marrying Prince Harry.

PALACE INVESTIGATING MEGHAN MARKLE, NOT PRINCE ANDREW, PROVES 'DOUBLE STANDARD' BY ROYAL FAMILY: AUTHOR

Meghan Markle is expecting her second child, a girl. (Getty)

"I didn’t fully understand what the job was," she said. She also noted that she did not know how to curtsy before meeting Queen Elizabeth II for the first time, and didn’t realize it would be necessary.

"I will say I went into it naively because I didn’t grow up knowing much about the royal family," Markle said. "It wasn’t something that was part of conversation at home. It wasn’t something that we followed."

Markle said she and Harry were aligned during their courtship because of their "cause-driven" work. But she did not fully comprehend the pressure of being linked to the prestigious royal family.

"There was no way to understand what the day-to-day was going to be like," she said. "And it’s so different because I didn’t romanticize any element of it."

CLICK HERE TO GET THE FOX NEWS APP

The Duke and Duchess of Sussex currently reside in California with their son Archie. (Getty)

Winfrey at various points in the interview ran through headlines about Markle and at one point asked about the mental health impact. Markle responded that she experienced suicidal thoughts and had sought help through the palace’s human resources department, but was told there was nothing they could do.

"I was really ashamed to say it at the time and a shame to have to admit it to Harry, especially because I know how much loss he suffered," she said. "But I knew that if I didn’t say it that I would do it. And I just didn’t, I just didn’t want to be alive anymore." 

The couple married at Windsor Castle in May 2018, and their son, Archie, was born a year later. Harry and Markle's departure from royal duties began in March 2020 over what they described as the intrusions and racist attitudes of the British media toward the duchess.

It is unclear what public reaction if any, the queen and other royal family members will have to Sunday’s interview. The U.K.’s Times newspaper, citing an anonymous source, reported that the queen, 94, would not watch it.

The Associated Press contributed to this report.