this week that the Duchess drove two personal assistants out of the household and undermined the confidence of a third.
Meghan strongly denies the allegations.
However, royal aides said they were left 'shaking with fear' following run-ins with the her - and Buckingham Palace has now announced a formal probe into the allegations.
In response to the reports, Meghan and Harry accused the Queen's staff of orchestrating a "calculated smear campaign" ahead of their explosive two-hour interview.
Thomas and Meghan share a father, Thomas Markle Credit: Channel 5 / Thomas Markle: My Story Meghan and her dad have had a difficult relationship for years, and he has repeatedly given interviews about his daughter Credit: refer to s But Thomas said: "Nobody recognises the Meghan we are seeing right now.
"I have seen her bully people before in the past and get her way, no matter what."
Meghan's claims that 'The Firm' are behind "falsehoods" about her and Harry isn't thought to be linked to the bullying probe - as the interview was recorded before the allegations surfaced.
In the clip, Winfrey asks Meghan: "How do you feel about the Palace hearing you speak your truth today?"
A visibly-emotional Meghan replies: "I don't know how they could expect that after all of this time we would still just be silent if there is an active role that The Firm is playing in perpetuating falsehoods about us."
She adds: "And, if that comes with risk of losing things, there is a lot that has been lost already."
But Thomas said he predicted that Meghan and Harry would step back as senior royals before Megxit went ahead.
And he believes his half-sister is behind the couple's move to LA.
“I think Meghan is the driving force behind all of this," he said.
"I called this a few years ago. I said she would be leaving the Royal Family and going back to California.
"Maybe it’s sad but I don’t think it’s in Harry’s best wishes."
Meghan Markle ‘blamed Kate, Camilla and Charles’s aides for leaking stories about her’