Mike Markle, 80, accused his royal niece of leaving her family behind – despite years of support from him and other relatives.
He told Woman Magazine that he first helped the Duchess of Sussex on her way to becoming a stateswoman when she was just 20 years old.
Former diplomat Mike secured her an internship as a junior press officer in the American embassy in Argentina when she was considering a career in international relations.
But now he fears Meghan has turned her back on her American family.
And he doubts he will ever hear again from the 38-year-old former actress – even though he would like it to happen.
Mike, who is the elder brother of her father Thomas, 75, said: “Meghan has climbed socially and left us behind — that’s how I feel.
I think that’s what happens when you’re ‘underclass’ and trying to rise above the reality of your situation. She’s a prima donna because he (Thomas) treated her really well
Mike MarkleMeghan’s Uncle
“I think that’s what happens when you’re ‘underclass’ and trying to rise above the reality of your situation.
“She’s a prima donna because he (Thomas) treated her really well.”
And the retired US diplomat shed light on the alleged rivalry between Meghan and the Duchess of Cambridge.
Of Meghan, he said: “Coming from her background, she may have a chip on her shoulder.
“It could be that that’s part of the problem she’s having with her sister-in-law.
“Meghan is immature in some ways.
“I feel that because of the way she acts — not only towards family members, but other people.”
He also said he felt deeply hurt at not being invited to Meghan and Prince Harry’s wedding.
‘PITTED AGAINST’ KATE
His scathing attack comes as a royal source claimed Meghan is keenly aware she’s being “pitted against” the future Queen Kate Middleton.
Both Meghan and Kate, the Duchess of Cambridge, have found the situation with one another “challenging”, the source told People magazine.
Meghan and Harry, 35, mum and dad to six-month-old baby Archie, recently opened up for a documentary about their struggle with being in the spotlight.
They were widely praised for their honesty in the emotional hour-long doc titled Harry & Meghan: An African Journey.
Presented by Harry’s pal Tom Bradby – the show followed the Sussex’s on their tour of the continent.
It gave viewers an insight into the pressures the royal couple face – with both Harry and Meghan baring all.
Meghan was close to tears as she described feeling “vulnerable” while speaking about being a new mum.
Prince Harry said he has grown apart from brother William – and also spoke about how the tragic death of his mother, Princess Diana, still haunts him.
He said: “I think being part of this family, in this role and this job, every single time I see a camera, every single time I hear a click, every single time I see a flash, it takes me straight back.”