Christopher Ciccone's relationship with his older sister, Madonna, was once so close that he described it as "a bit like a marriage."
"I was the last person she spoke to at night before she went to bed," he told ABC's "Good Morning America" today. "I was the first person she saw in the morning."
All that changed after Madonna married Guy Ritchie. Ciccone, who is gay, said Ritchie's homophobia drove him and his sister apart.
And like a spurned spouse or jealous lover, Ciccone is now spilling secrets about his sister in his tell-all memoir, "Life with My Sister Madonna," which hit bookstores today.
"It's basic envy," psychoanalyst and family therapist Bethany Marshall told ABCNews.com about why Ciccone's has written a book about his famous sister. "When we feel envious, we want to destroy the object of our envy and bring them down, so we don't have that reminder that we are missing out on something we want."
What's missing besides the closeness he once shared with his sister is the income Ciccone once earned over two decades as a designer, choreographer, director and yes man for Madonna.
"If he was on the Madonna gravy train and she cut him off, he could feel like he's going to get his no matter what, one way or the other," Marshall said. "When people operate at primitive levels and get their feelings hurt or nose out of joint, they always want the other person to pay for making them feel neglected or like a failure."
Ciccone, 47, insisted to "GMA" that he did not write the book to get back at the pop superstar. "I'm not taking revenge at all,'' he said. "I'm telling what I consider to be a great tale."
But Sara Nelson, editor of Publisher's Weekly, has no doubt that Ciccone was paid well by his publisher, Simon Spotlight Entertainment, a subsidiary of Simon and Schuster. "At least half a million, I would think," she said.
The larger the advance, the more the publisher is counting on the book selling.
"Celebrity books, when done right are sure sellers," Nelson told ABCNews.com. "There have been a lot of books about Madonna, just like books about Princess Diana. If they have the right characteristics, they can do very well. Andrew Morton had a certain inside track with Diana. This is Madonna's brother -- somebody who knows her."
Albert Lee, a senior editor at US Weekly, has seen these celebrity tell-all books, like Nancy Anniston's 1999 "From Mother and Daughter to Friends: A Memoir" about daughter Jennifer, come and go, usually after a relative is cut off financially or emotionally from his or her famous family member who is the family breadwinner.
"Some kind of estrangement happens," "Lee told ABCNews.com, "and the sibling or parents gets offered an insane amount of money [by a publisher]. They come out with a book, and the celebrity's publicist releases a statement saying they are disappointed, it's all lies."
But Lee believes readers of Ciccone's book can expect some new revelations about Madonna.
"Who better than a family member to give real insight into what celebrities are like," Lee said. "Christopher and Madonna were superclose, incredibly close for a very long time. It's almost surprising in this day and age that [this book] didn't happen sooner."
The timing of the book couldn't be better for Ciccone, according to Nelson. Madonna has been in the news the last few weeks over rumors that her marriage to Ritchie is on the rocks and that her friendship with Yankee slugger Alex Rodriguez has cost him his marriage to Cynthia Rodriguez.
"The timing is fortuitous," Nelson said.
And not just for Ciccone. Lee said Madonna is benefiting as well from the publicity around the book. "I think Madonna is enjoying every minute of this attention," he said. "When she was flouncing around in the '80s singing 'Like a Virgin,' did you think we'd still be talking about Madonna, that she's still relevant at 49? I think she's genuinely mad, but she's also loving the attention."
Does that mean she'll forgive her brother for writing it?
"He's shot any chance of reconciliation," Lee said. "Madonna has a long memory. The only way a celebrity's relative could write a book about the celebrity and not totally destroy the relationship is by having that celebrity's blessing in a big way."
Jennifer Anniston's mother, Nancy, found that out the hard way. Anniston was apparently so angry with her mother for writing about her appearance before her nose job and other intimate details that she excluded her from her wedding to Brad Pitt.
When talk show host and publishers' biggest booster Oprah Winfrey found out her father, Vernon, was shopping around a memoir about raising his famous daughter, she told reporters she was "stunned."
"The book was stopped and went away," Nelson said.
Will the public buy Ciccone's book?
"The public likes these books," Nelson said. "But it's going to depend on the tone of this book. I'm not the only person who thinks what a creepy brother to do that to his sister. If the book has a gleeful viciousness, it could be a problem. If the tone is more measured, and we sympathize with him, that could help him. At the moment, the implication is he got mad and is going to air her dirty laundry, and that's could hurt him."
Marshall, the family therapist, believes the public enjoys these books because of envy. "We want to see our stars fall," she said. But we also like to see them redeemed. "When they fall off the pedestal and get back on -- we've all that had experience," Marshall said.
As for Ciccone's book, "The public is really smart and recognizes dysfunction," she said. "But they'll still want to read it. It'll probably be a best-seller."
"But I think it's a hollow victory for him," she added. "It's like the kiss of Judas. When you have to betray another person to get your needs met, it's never truly satisfying."