The 38-year-old is suing a British newspaper for publishing a personal letter she sent to the former Hollywood lighting director in August 2018. The 75-year-old alleged he will be a witness in court in the hopes of shedding light on the “lies” that were told about him.
“It will be emotional,” said the patriarch, as reported by UK’s Daily Mail on Monday. “I don’t know how we will both accept it.”
“It would be the worst place to have to meet her and [Prince] Harry — but it might come down to that because I will certainly testify against the things that have been said about me,” he continued. “The lies.”
According to the outlet, Thomas has given attorneys previously unseen text messages that reveal the breakdown of the relationship between father and daughter.
“I’m tired of being lied about and not being defended,” he explained. “I put the newspaper in this position by offering up a portion of that letter, which led to them being sued. This is my fault so I have to stand up for myself. It’s a responsibility thing.”
In a documentary that aired last week on U.K.’s CBS Channel 5, Thomas detailed Markle’s childhood in Los Angeles, her rise to fame in Hollywood, as the role her husband has played on their estrangement. He also confessed he once lied about her and the British royal to “Good Morning Britain” host Piers Morgan when he was interviewed after he missed their royal wedding.
"I said [that] they called me back and they were really concerned about me and I said, 'Go on your honeymoon, don't worry about me. I'll be fine.' And that was all a lie," Thomas told the interviewer.
"So I made their image appear a little bit better," the outspoken father added.
Thomas remarkably came under fire in 2017 ahead of Markle's lavish royal wedding ceremony to Harry in a staged paparazzi photoshoot in Mexico. He admitted he regretted the "stupid and hammy" shots, which Markle's estranged half-sister Samantha Markle later admitted to orchestrating.
He was scheduled to walk his daughter down the aisle at St. George's Chapel at Windsor Castle, but days before the wedding he reportedly suffered a heart attack and underwent heart surgery.
Thomas also told Channel 5 he lied to Harry about his regrettable photo shoot.
"I denied it," he revealed. "All Harry asked me was did I pose for measurements for a suit, and I said, 'No, I wasn't posing for a measurement for a suit, I was being measured for a new hoodie.' That's what I told them."
He added: "Of course that was a lie. I lied to him. I'm not proud of that, but I did."
Thomas sat down with Channel 5 over a span of six days back in October, just three months ahead of the couple's announcement that they would be "stepping back" as senior members of the royal family.
The Duchess of Sussex filed a claim against the Mail — and its parent company Associated Newspapers — alleging "the intrusive and unlawful publication of a private letter written by" Markle.
"There is a human cost to this relentless propaganda, specifically when it is knowingly false and malicious, and though we have continued to put on a brave face – as so many of you can relate to – I cannot begin to describe how painful it has been," Harry wrote. "Because in today’s digital age, press fabrications are repurposed as truth across the globe. One day’s coverage is no longer tomorrow’s chip-paper.
"Up to now, we have been unable to correct the continual misrepresentations — something that these select media outlets have been aware of and have therefore exploited on a daily and sometimes hourly basis," he continued, noting that this is why the Sussexes have decided to take legal action.
Harry said the decision to sue "may not be the safe" choice, but it is "the right one."
"Because my deepest fear is history repeating itself," he continued. "I’ve seen what happens when someone I love is commoditized to the point that they are no longer treated or seen as a real person. I lost my mother and now I watch my wife falling victim to the same powerful forces."
Fox News’ Melissa Roberto and Mariah Haas contributed to this report.