"William is devastated by this interview. Don't forget that the Duchess of Cambridge is being dragged into this whole saga and William will hate that and of course, relationship between father and son is of course at an all-time low," Nicholl says. "I think that the idea that Kate’s being dragged into this will be upsetting for Kate who behind the scenes has tried really hard to be a peacemaker between William and Harry. She has been deeply saddened by the brothers' falling out. Don’t forget she was incredibly close to Harry herself."
Nicholl said it's unclear what type of relationship Meghan, Harry, Will and Kate will have in the future. Harry said during his interview with Oprah that although he and Will are taking time apart right now and are on different paths, he will always love his older brother.
"Harry has said time is a healer and it is," she notes. "But I think there are so many raw emotions here, that it's far too early to talk about any kind of family reunion."
As for Harry's comments that he felt his dad and brother were trapped, Nicholl says it's an unfair comment on Harry's part.
"Harry was born in a very different role than William -- he was born the spare, William the heir," she explains. "William has always known what his duty and birthright has been. I’m sure there's times when he's resented the establishment he's born into and there's been times he's kicked back at it... There are times certainly when William has struggled with his birthright, but to suggest that he's trapped in the institution, I don’t think it’s true and I don’t think it’s probably Harry’s place to say in any case."
As for Prince Charles, Nicholl says a source close to the 72-year-old royal told her that he was "despairing over the interview" days before it went out. Indeed, Harry made unflattering comments about his father, claiming that he stopped answering his calls when discussing his and Meghan's royal exit.
"There came a point where Charles simply didn’t want to hear anymore what Harry and Meghan were proposing," Nicholl tells ET. "Instead, he asked him to put in an email, something Harry didn’t want to do because he was convinced it would leak and Harry was absolutely right. It did leak to the press and that's why he took matters into his own hands."
"Charles certainly does not come out a winner in all of this," she adds. "Harry has said he felt let down by his father. It must have been a very difficult thing for Harry to say publicly, but even a difficult thing for Prince Charles to hear. ... Certainly, in the run-up to the wedding, Charles was supportive of them. He was thrilled on the day to walk Meghan down the aisle. He and his son, Meghan and [his wife] Camilla, had a close relationship at that time that Charles invited them to come stay with them at the castle in Scotland -- a privilege that not many people are afforded. So, this closeness quickly turned into resentment and detachment when Charles wouldn't sit down and discuss what Harry and Meghan wanted for the future on the phone and that's when we understand the relationship unraveled. But for Charles to hear that he felt let down by Harry will be very, very painful indeed."
During his sit-down with Oprah, Harry said he wanted to heal his relationship with his father.
"There's a lot to work through there, you know?" he acknowledged. "I feel really let down, because he's been through something similar. He knows what pain feels like, and this is-- and Archie's his grandson. But, at the same time, you know, I-- of course I will always love him, but there's a lot of hurt that's happened. And-- and I will continue to make it one of my priorities to try and heal that relationship."
As for Will, he noted, "I love William to bits. He's my brother. We've been through hell together. I mean, we have a shared experience. But we-- you know, we're on-- we're on different paths."
For more on Meghan and Harry's shocking revelations, watch the video below.