Ronald Reagan's Daughter Warns Prince Harry 'There Isn't Just One Truth' Before Bombshell Memoir Slamming Royal Family Hits Shelves

Patti Davis revealed she eventually apologized to her father, who later passed away in 2004, for writing the book.

As Prince Harry's highly anticipated memoir, Spare, is set to hit shelves on Tuesday, January 10, Ronald and Nancy Reagan's daughter is opening up on the hard lessons she learned from penning her own tell-all.

Patti Davis — who released her book, Family Secrets, in 1993 — admitted that she would have decided to stay "quiet" for longer if she had the chance to do it all over again.

"My justification in writing a book I now wish I hadn’t written…was very similar to what I understand to be Harry’s reasoning," the 70-year-old explained in a recent OpEd. "I wanted to tell the truth, I wanted to set the record straight."

Added Davis, "Naïvely, I thought if I put my own feelings and my own truth out there for the world to read, my family might also come to understand me better."

The former First Daughter revealed she eventually apologized to her father, who later passed away in 2004, while he was in the early stages of Alzheimer's and still had "lucid moments." She also drew parallels between her final years with the former President and the Duke of Sussex's relationship with King Charles III.

"I thought of that moment when I read that Prince Harry, in his new memoir, wrote about his father, King Charles, getting between his battling sons and saying, ‘Please, boys, don’t make my final years a misery,'" she continued. '"Time is an unpredictable thing…I had the gift of time with my father, which allowed me to apologize, even though a disease hovered between us and clouded our communication. King Charles’s words reveal a man who is aware of his mortality and who would like his offspring to be aware of it as well."

Davis later noted that writing her book taught her valuable lessons about family relationships and what speaking openly about their private affairs can do to them.

"People generally don’t respond well to being embarrassed and exposed in public. And in the ensuing years, I’ve learned something about truth: It’s way more complicated than it seems when we’re young," she shared. "There isn’t just one truth, our truth — the other people who inhabit our story have their truths as well."

Finally, Davis confessed that if she had the opportunity to speak to her younger self before writing her memoir, she would have said two words: "Be quiet."

"Not forever. But until I could stand back and look at things through a wider lens," she wrote. "Until I understood that words have consequences, and they last a really long time."

Pointing out that Harry not only referred to Prince William as his "beloved brother" but also as his "arch nemesis," she warned that those words "leave a scar" and if he had "taken time to be quiet," he may have chosen those words differently.

Davis wrote the OpEd for the New York Times.