From the moment Meghan Markle entered the royal family, someone from her own family hovered like a spectre over her glittering future.

Like something out of a Disney fairytale, as Meghan pursued a new life with her prince, her older half-sister Samantha cast doubting shadows on her sibling's do-gooder image, calling her a "duchass", comparing her to Donald Trump and most recently appearing on TV to tell the world, "I told you so" as Megxit erupted.

Speaking exclusively to Newstalk ZB's Heather du Plessis-Allan, Markle says she had hoped her sister and husband, Prince Harry, would have had "the tenacity" to stay in the roles the pair revealed were making their lives miserable.

"Oh God. Well, yeah, I was a little bit surprised that they would step down. I was hoping they would have the tenacity to stick it out or change what they were doing wrong that created so much public controversy. I thought they would own up to the package that they signed up for."

Noting the impact media scrutiny has had on Meghan and Harry, Du Plessis-Allan asked Samantha if she is at all concerned for her sister.

"Obviously what they're going through is intense ... It would have a huge impact on someone's mental health. Do you worry about her?" asked the broadcaster.

"In all fairness and honesty, I think she has demonstrated no concern for our family and the royals. I'm not going to be the first one sitting in the back of the classroom saying, 'Oh, pick me. I'm going to defend her' ... she's an adult. She made choices. Harry made choices and those choices had deleterious consequences for our family, for the royals and for so many charities ..."

Pressing the 53-year-old on the issue of how Meghan might be coping, du Plessis-Allan interjects saying, "Samantha, that's a fair point but it doesn't make it any easier for her, does it?"

Samantha claims Meghan owes her father and the royal family an apology. Photo / AP

"It's not all about her. How about whether or not it's easier for everybody else. For the royals and for our family and for other people in the world who relied on her and who relied on them.

"It is not about her feelings. Just like when she took the opportunity at the end of that documentary about starvation in Africa to say, 'Oh, I'm glad somebody's worried about me. My life as a royal is not easy.'

"You don't do that when you're talking about starvation. You don't do that on the world stage. Really? It's kind of like poor pitiful her. No, I'm not too worried about her. I think she's done a lot of damage to a lot of people and I think she needs to own up to it and be accountable. Be gracious, be a lady and be a humanitarian. And make things better and apologise."

Markle said Meghan should be apologising to their father as he'd given her "an amazing life" being a sole parent for most of her life.

"When people ask us questions we answer honestly ... we're not going to candy-coat the truth, she has treated people horribly," she said.

"He shouldn't have to go through this and grovel.

"Screw her reputation, she needs to be an adult and do the right thing."

"Parents don't expect to be paid back but they expect a little bit of gratitude ... without him she would be a waitress at best. She's an absolute sociopath if she doesn't humble herself to do the right thing."

"Are you jealous of her?" du Plessis-Allan asked.

"Am I jealous? No, I'm embarrassed, I'm hurt for my dad," Markle responded.

"That's my story and I'm sticking to it and she owes a lot of people apologies.

"The royals welcomed her into their lives with open arms, made her one of the fab four ... and I just feel like she tossed it aside like a dish rag, and that part of it is shocking."