Kate Middleton's uncle, Gary Goldsmith, has come under fire and was branded the "black sheep" of the Middleton family for revealing details about his niece and her husband in an exclusive interview.

Goldsmith, who is known in the family as "Uncle G," has been accused of betrayal for disclosing details about the life of the Duchess of Cambridge through a deal with Hello! The article is 16 pages with exclusive family photos for a cover story titled, The Kate I Know. It was negotiated by Goldsmith's agent, according to Mail Online.

Goldsmith, the younger brother of Kate and Pippa Middleton's mother, Carole, divulged details about his niece related to vacations she spent at his Ibiza villa, nicknamed La Maison de Bang Bang.

"Uncle G" said that his niece and her husband learned to DJ at his massive Ibiza pad, the couple took mud baths there together and that he may have helped play a part in helping his niece and Prince William get back together during their temporary separation in 2007.

Goldsmith said his sister Carole, Kate's mother, had asked him to let her daugher stay at his Ibiza home to "get away from everything" when she broke up with William. His niece stayed at his home because it's a "very relaxing place and it has a very nice vibe and you can hear the sea at night," he said. Kate spent most of her time talking on the phone, walking around the pool and she was feeling very "low," he said of her stay. The coupe reconciled shortly after that time so Goldsmith said he likes to feel like he may have "helped" the couple patch things up.

Goldsmith asked if the Middleton sisters are different he said "they are different."

"Kate works really hard at everything," Goldsmith told HELLO! "She is brilliant at whatever she turns her hand to, but works at it, throwing herself into everything. Whereas Pip, everything seems to come very easily."

The HELLO! article features a photo spread with pictures taken of Goldsmith at his Ibiza mansion where the royal couple stayed. La Maison de Bang Bang is up for sale and reports claim that he provided details about Middleton's personal life in exchange for a hefty sum and because it will help increase his chances of selling the home. The estate is on the market for $8.5 million.

Goldsmith said he intends to write an autobiography, and the book will be about his "experiences at the heart of the Middleton clan."

Mail Online asked a St James' Palace rep to comment on the story. "We are not commenting on the grounds that we wouldn't comment on private conversations between members of the Middleton family," said the rep. 

Tags: Kate Middleton