In his latest rant, he accused the Duchess of Sussex of cutting him out of her life and claimed the Royal Family were trying to “silence” him.
He even dragged Princess Diana into the row by saying the late princess would have “loathed” the way he has been treated.
And royal commentator Richard Fitzwilliams said Mr Markle’s latest comments would further infuriate the Windsors.
Mr Fitzwilliams told Express.co.uk: “Thomas Markle should have known that such a contentious and highly personal interview would be anathema to the Royal Family.
“His comments about what Princess Dianawould have thought will be particularly contentious.
“The Royal Family have changed a good deal since the tragic death of Diana 21 years ago.
“It is clear that Mr Markle’s remarks will not endear him to Princess Diana’s sons, Prince Harry and Prince William.
Meghan Markle’s estranged father has angered the Royal Family, an expert said
“If Diana were still with us, I think she would wish that Harry and Meghan are happy together which they undoubtedly are.”
Prince Harry was aged just 12 when his mother died in a car crash in Paris in 1997.
Speaking to the Mail on Sunday, Mr Markle said: “I tell you, I’ve just about reached my limit with Meghan and the Royal Family.
“They want me to be silent, they want me to just go away. But I won’t be silenced. I refuse to stay quiet.
Meghan Markle married Prince Harry at Windsor Castle on May 19
“They have Meghan treating her father in a way that Harry’s mother Princess Diana would have loathed.
“That’s not what Diana stood for. Princess Diana is credited with changing the Royal Family but she wasn’t perfect.
“She was still very much one of them. I think Meghan’s the one who’ll bring them into the 21st century, if they’ll let her.”
Responding to his rant, Mr Fitzwilliams added: “It is impossible to guess how this will play out, but it is a sad and sorry business.
Prince Harry was aged just 12 when his mother died in 1997
“Thomas Markle says he ‘won’t be silenced’ but giving interviews to the press is not the way to win the trust of the Royal Family.”
Buckingham Palace did not comment on Mr Markle’s latest outburst.
Meghan Markle married Prince Harry at Windsor Castle on May 19 in a ceremony watched by a worldwide TV audience of 1.9 billion people.