Prince Harry Addresses William's Alleged Physical Attack, Why He Didn't Fight Back

The interview comes just days ahead of the release of Harry's tell-all memoir, 'Spare,' out Jan. 10.

Prince Harry is sharing more details about the alleged altercation between him and his brother, Prince William.

In a new interview with ITV's Tom Bradby Sunday, Harry opened up about the alleged physical attack, detailed in his tell-all memoir, Spare, out Jan. 10, and explained why he didn't fight back.

The Duke of Sussex, who said he and William used to "fight all the time like a lot of siblings," said he would have 100 percent fought William in the heat of that alleged 2019 altercation had it not been for therapy.

"I can pretty much guarantee today, that if I wasn’t doing therapy sessions like I was and being able to process that anger and frustration, that I would’ve fought back, one hundred percent," Harry told Bradby.

In an excerpt read from his autobiography Harry read, "Come on, hit me, you’ll feel better if you hit me…Come on, we always used to fight, you’ll feel better if you hit me."

"No, only you’ll feel better if I hit you. Please, just leave," Harry said he replied.

Harry spoke more about the tense moment between him and his brother during his 60 Minutes interview with Anderson Cooper, which also aired Sunday.

"It was a buildup of -- frustration, I think, on his part. It was at a time where he was being told certain things by people within his office," Harry told Cooper of the argument, which reportedly started over Harry's wife, Meghan Markle. "And at the same time, he was consuming a lot of the tabloid press, a lot of the stories. And he had a few issues, which were based not on reality. And I was defending my wife. And he was coming for my wife. She wasn’t there at the time, but through the things that he was saying."

He continued, "I was defending myself. And we moved from one room into the kitchen. And his frustrations were growing, and growing, and growing. He was shouting at me. I was shouting back at him. It wasn’t nice. It wasn’t pleasant at all. And he snapped. And he pushed me to the floor."

The alleged altercation, which the 38-year-old father of two called a "pretty nasty experience," first came to light earlier this week, after The Guardian published an excerpt from Harry's memoir.

Per the outlet, Harry claims William called Meghan "difficult," "rude" and "abrasive," something Harry called a "parrot[ing of] the press narrative" about his wife.

Insults were exchanged before Harry says William swore while stepping towards him. Harry, now scared of his older brother, said he walked to the kitchen, where an angry William followed. Harry claims he tried to calm his brother down and offered him a glass of water.

"Willy, I can’t speak to you when you’re like this," Harry writes, per The Guardian.

The excerpt continues, "He set down the water, called me another name, then came at me. It all happened so fast. So very fast. He grabbed me by the collar, ripping my necklace, and he knocked me to the floor. I landed on the dog’s bowl, which cracked under my back, the pieces cutting into me. I lay there for a moment, dazed, then got to my feet and told him to get out."

Harry claims that William urged him to hit back, referencing fights that they had growing up. Harry said he refused to do so, prompting William to leave. He later returned, Harry says, "looking regretful, and apologized."

William reportedly urged Harry not to tell Meghan about the fight, and while Harry did not immediately tell his wife, he writes that he called his therapist.

But the "scrapes and bruises" were soon noticed by Meghan, forcing Harry to tell her about the alleged attack. While he says the former Suits actress "wasn't that surprised, wasn't all that angry," she was "terribly sad."

Following the release of the now-viral Spare's excerpts, a source close to the Royal family tells ET that the royal family says William is "furious" with his younger brother and feels that Harry has "crossed a line."

The royal family "is bracing themselves for the next round of allegations" from Harry's interviews on Sunday, the source shared, noting that Prince William is not only "furious," but he "feels Harry has crossed a line."

"The family is appalled that Harry has revealed such private and lurid details which are completely inappropriate," the source continued, adding that no one thought Harry would go this far and share this much.

As for that reconciliation, Harry said he's hoping for it, but several sources ET spoke to said it would take time to restore trust within the family.