(The Hill) – Prince Harry and Meghan Markle, the Duke and Duchess of Sussex, have garnered headlines in the past few years after stepping back from being senior members of the British royal family in 2020.

Many more revelations behind the circumstances of their departure and other rarely publicized details about the royal family are set to be in the spotlight when Harry, 38, is releases his new autobiography, “Spare,” which is set to hit bookshelves on Tuesday.

In it, he acknowledged his struggles with depression and grief after the death of his mother, Princess Diana, and his fractured relationship with his family. 

Here are five things to know about Prince Harry’s new book. 

Sibling Rivalry with Prince William 

Harry wrote in his new book that he had a “sibling rivalry” with his older brother, Prince William, writing that he and his brother lived separate lives following their mother’s death  while the media portrayed them to be loving brothers. 

During an appearance on CBS News’ “60 Minutes,” Harry acknowledged to Anderson Cooper that William told him to, “Pretend we don’t know each other” while they were in secondary school, which Harry cited as a particular moment that hurt him. 

“I couldn’t make sense of it,” Harry told Cooper. “I was like, ‘What do you mean? We’re now at the same school. Like, I haven’t seen you for ages, now we get to hang out together.’ He’s like, ‘No, no, no, when we’re at school we don’t know each other.’ And I took that personally.”

“Like, we had a very similar traumatic experience, and then we — we dealt with it two very different ways,” Harry added, referencing Princess Diana’s death.

Harry also noted in his new book that he got into a physical altercation with William in 2019 about his wife, Meghan, saying that William knocked him on the ground, resulting in him having a visible injury to his back. 

He thought Diana disappeared when she died

Harry also wrote about his late mother, Diana, who died in an automobile accident in 1997 when he was 12 years old, saying that he thought his mom initially disappeared

“You didn’t believe she was dead,” Cooper asked Harry. 

“Unh-uh. For a long– for a long time, I just refused to accept that she was– she was gone,” Harry replied. “Um, part of, you know, she would never do this to us, but also part of, maybe this is all part of a plan.”

“I mean, you really believed that maybe she had just decided to disappear for a time?” Cooper asked Harry. 

“For a time, and then that she would call us and that we would go and join her, yeah,” Harry replied, noting that he and William had discussions about the thought of their mother reappearing one day. 

The “60 Minutes” interview also cited Harry insisting to see photos of the crash scene for “proof that she was in the car.”

He credits his military career with saving him

Harry also wrote in his new autobiography about how his service in the British military saved his life, telling Cooper in the sitdown interview that he was able to find normalcy during his tenure. 

“Got me out of the spotlight from the — from the U.K. press. I was able to focus on a purpose larger than myself, to be wearing the same uniform as everybody else, to feel normal for the first time in my life,” Harry told Cooper, noting what he considered to be major accomplishments such as training to become an Apache helicopter pilot. 

He also said his military service helped him cope with losing his mother.

“It felt like I was turning pain into a purpose,” Harry said. “I didn’t have the awareness at the time that I was living my life on adrenaline, and that was the case from age 12, from the moment that I was told that my mom had died.” 

He used psychedelics to cope with grief

Harry also opens up about drug use in his new autobiography, writing that he tried marijuana and used cocaine to cope with the loss of his mom and also used psychedelic drugs as a form of treatment. 

Harry told Cooper that he used psychedelics such as ayahuasca, psilocybin and mushrooms. 

“I would never recommend people to do this recreationally,” Harry said.  “But doing it with the right people if you are suffering from a huge amount of loss, grief or trauma, then these things have a way of working as a medicine.” 

Harry added that the using the psychedelic drugs helped him clear “the windscreen of the misery of loss.” 

“They cleared away this idea that I had in my head that– that my mother, that I needed to cry to prove to my mother that I missed her,” he added. “When in fact, all she wanted was for me to be happy.” 

He asked his father not to marry Camilla

Harry also said that he and his brother asked their father, now King Charles III, not to marry his now stepmother, Queen Consort Camilla, saying he considered her to be dangerous for how badly she wanted to rehabilitate her image after Diana revealed Camilla to be the third person in their marriage.  

“You and your brother both directly asked your dad not to marry Camilla?” Cooper asked Harry.

“We didn’t think it was necessary,” Harry replied. “We thought that it was gonna cause more harm than good and that if he was now with his person, that– surely that’s enough. Why go that far when you don’t necessarily need to?  We wanted him to be happy. And we saw how happy he was with her. So, at the time, it was, ‘OK.’ 

Harry also referred to his stepmother as “dangerous” due to her connections with the British press.

“That made her dangerous because of the connections that she was forging within the British press. And there was open willingness on both sides to trade of information,” Harry said. “And with a family built on hierarchy, and with her, on the way to being queen consort, there was gonna be people or bodies left in the street because of that.”