Harry still has ongoing cases against the publishers of The Sun and Daily Mail over allegations of unlawful snooping.
"I was an easy target," the "Ally McBeal" star told The New York Times.
The fashion designer said it was “the most unhappy I have ever been in my entire life.”
Harry's presence during three days of the legal wrangling indicates the lawsuit’s importance in the prince’s broader battle against the British press.
“The Institution made it clear that we did not need to know anything about phone hacking," the Duke of Sussex wrote in a witness statement for his lawsuit.
"These articles are a strategy to now blame her for MY every word and move," the "Good Place" actor said.
The Duchess of Sussex is suing Associated Newspapers for publishing parts of a private letter she wrote to her father, Thomas Markle.
The Duke and Duchess of Sussex listened in on the preliminary hearing in Britain's High Court and are said to be encouraged by the process so far.
The Duke and Duchess of Sussex condemned British tabloids, including the Daily Mail, for stories they said were "distorted, false, or invasive beyond reason."
"I lost my mother and now I watch my wife falling victim to the same powerful forces," Harry wrote in the letter.