In hindsight, he admits Harry was "absolutely right" to criticise him.
Today, in his most explosive interview yet, Mr Markle also confesses that he lied to the Prince when Harry asked him if he had co-operated with a paparazzi photographer to pose for shots - one of which showed him apparently being fitted for a wedding suit.
"If you treat your own father like this, Harry is next", she claimed.
ICYMI, Meghan and Thomas Sr.
The Apprentice star said: "I thought you were a good friend of hers?"
Mark Blinch / Reuters Meghan Markle watches the closing ceremony of the Invictus Games with her mother Doria Ragland in Toronto on September 30, 2017.
"Doria made the very hard decision to leave her job at the clinic because there had been a lot of calls from the media asking to speak with her because her daughter was marrying Prince Harry", a source told the magazine.
However, Kensington Palace is "less concerned" about Samantha than Thomas, the source notes, "because she has never had a real relationship with Meghan".
According to reports, Meghan's mam Doria Ragland is making the move to the United Kingdom to be closer to her daughter.
Meghan's November 2017 engagement to Harry coincided with her decision to quit acting and she subsequently departed Suits in Season 7, in which her character was similarly set to Wednesday.
"She is getting ready to move to London", the source claimed. Mr Markle told his soon-to-be son-in-law that he was simply being "measured for a hoodie".
Writing in her now-closed Instagram account, Meghan revealed: "I used to have lunch with my dad here after every tap & ballet class. She also fell in love with England and told me when she got back that it's somewhere she believes she too could happily live".
Meghan Markle and Prince Harry got engaged in November 2017 and were married at Windsor Castle on May 19th, 2018. "That's what makes pieces special, the connection you have to them".