Sarah Ferguson Says She Told Daughters Beatrice and Eugenie Growing Up: 'I've Already Made Those Mistakes'

Sarah "Fergie" Ferguson is a proud mom — and she says she raised her daughters to avoid the pitfalls she experienced in her own life.

"I'm self-deprecating and British. But [one thing] is I'm a really good mom," the Duchess of York, 61, tells PEOPLE exclusively in this week's cover story.

"And I'm a good mom because, in growing up, when the girls used to say, 'Why can't we do that?'" she says of Princess Eugenie, now 31, and Princess Beatrice, now 32. "I would say, "Well, I've already made those mistakes. The world's press has written about my mistakes, so you don't need to make them now. So I've gone ahead of you to clear the way so that you can dream and grow and be who you are."

sarah ferguson
sarah ferguson

David Burton Sarah Ferguson in PEOPLE Magazine.

Watch the full episode of People Cover Story: Sarah Ferguson on PeopleTV.com or on the PeopleTV app.

A frequent tabloid target throughout much of her time in the spotlight, the Duchess — whose debut novel, Her Heart for a Compass, is due August 3 — says she has learned to make peace with her past.

her heart for a compass by sarah ferguson
her heart for a compass by sarah ferguson

Sarah Ferguson's new novel, Her Heart for a Compass.

She recalls, "Someone asked me, 'If you were an astronaut and you could take all the pressure off you, would you leave behind Fergie and Sarah and the Duchess and your past mistakes and failings?'"

sarah ferguson with her daughters
sarah ferguson with her daughters

Tim Graham/Getty Sarah Ferguson with her daughters, Princess Eugenie (left) and Princess Beatrice in 1994.

"And I said, 'What are you talking about? They're all my friends.' I made friends with past mistakes. I made friends with Fergie. She didn't know any better. And then Sarah. That's why we experiment. How is it that we're meant to be knowledgeable when we don't know? My Fergie, my Duchess, my Sarah: They're all good people."

Listen below to our daily podcast PEOPLE Every Day for more on PEOPLE's cover story interview with Sarah 'Fergie' Ferguson.