NBC News obtained court documents filed in London's High Court of Justice by her legal team as part of the duchess' case against the Daily Mail.
At the heart of the ongoing legal battle is the London tabloid's publishing of a private letter sent by the former Meghan Markle to her estranged father, Thomas Markle, four months after he missed her 2018 wedding to Prince Harry. The Daily Mail also published excerpts from the court documents on Wednesday.
The duchess said in the legal filing that she did not know one of her friends would mention the letter while speaking anonymously with People magazine. The Daily Mail has questioned that denial.
The court filing also states that she did not know about the February 2019 People article until the day it was published and didn't learn who the anonymous friends were who spoke with the magazine until much later.
Days after the People story ran, the Mail on Sunday published the private letter.
In it, Meghan begged her father to "stop lying and creating so much pain" and said his actions had broken her heart into "a million pieces."
Meghan's legal team called publishing the letter a "gross violation" of privacy.
The court documents also make multiple references to Meghan's mental health struggles, from feeling "unprotected" by the royal "institution," to feeling "vulnerable" when she was pregnant with her 1-year-old son, Archie.
Her assertions echo an interview with London's ITV in October in which she said she struggled under the intense media spotlight during her pregnancy and as a new mother. She also hinted at a lack of support from the royal family by saying "not many people have asked if I'm OK."
The court documents also reveal that her 2018 royal wedding produced "tourism revenue of over one billion pounds" for Britain, which is more than $1.3 billion.
She and Harry are now settling into their new life in Los Angeles, where she spoke about the Black Lives Matter movement and racial injustice in a video address to her high school alma mater last month.
"My wife said recently that our generation and the ones before us haven't done enough to right the wrongs of the past," he said. "I, too, am sorry. Sorry that we haven't got the world to the place that you deserve it to be."