Actress Angelina Jolie knew full well that adopting a Cambodian child would destroy her marriage to Billy Bob Thornton — but she decided to adopt the baby anyway, The ENQUIRER has learned.

That shocking revelation is one of many fascinating disclosures contained in personal journals written by the “Lara Croft: Tomb Raider” star, sources say. The journals form the basis for a new book to be published this summer by Pocket Books.

The ENQUIRER got an exclusive sneak peek at Angelina’s stunning autobiographical confessions, which also reveal that she questioned Billy Bob’s fitness as a father, suspected him of infidelity, and began to see their life together as superficial.

“Angelina sensed it was a quid pro quo — baby for husband — and she was willing to pay that price to take this baby home,” a source familiar with Angelina’s journal told The ENQUIRER. “She chose Maddox over Billy Bob and it’s a choice she has never regretted.”

The 2-year marriage of Angelina and Billy Bob was famous for the couple’s wild ways, including wearing vials of each other’s blood on a necklace and tattooing themselves with each other’s names. But the relationship ended last year when they separated just 11 days after Angelina brought baby Maddox to the States in May. Later, on July 17, Angelina filed for divorce.

“Billy Bob really had no interest in having a fourth child to support,” said the source. “He was crazy in love with Angelina but wasn’t buying into fatherhood. He wanted to get out on the road with his band, play music, hang out with the boys and his sexy wife. Diapers and midnight feedings weren’t his idea of wedded bliss.

“But Angelina felt desperate to be a mother. She and Billy Bob had discussed having children — much to his discontent — and the idea was in her head when she was touring refugee camps and orphanages in Pakistan, Africa and Cambodia.

“When she saw this boy baby in a Cambodian orphanage, she writes that he wrapped his hands around her heart. She was overwhelmed by his innocence. It took her outside of herself — here was a human life that needed her.”

Although Billy Bob visited Maddox in Cambodia with Angelina, the actress sensed she was alone in her baby dream, the source said.

“Angelina said, ‘He was a million miles away,'” the source told The ENQUIRER. “She said he objected to the adoption of Maddox on the grounds that they should have their own child, rather than raise a homeless baby. And that was the turning point for Angelina.”

“This child had reached into my soul and we were bonded,” she said later, according to the source. “It was a choice of no baby or no husband, of wearing a vial of blood around my neck or cradling a baby in my arms. The choice wasn’t difficult. I had to take Maddox home — at any price.”

Angelina already had major reservations about her marriage, the source said.

“She’d heard too many whispers that he was playing around and she did not want a marriage based on mistrust,” said the source. “She was no longer willing to live consumed by fears that at any time he could be in the arms of another woman. Her world had expanded and she needed more.”

Angelina’s position of goodwill ambassador for the United Nations High Commission for Refugees in 2001 had changed her, an insider told The ENQUIRER.

“It took her into a world far from Hollywood,” the insider said. “Clearly, her new world wasn’t a world that included Billy Bob. Her relationship with him seemed shallow, selfish and irrelevant. She saw the end of one life and the start of the next and bravely accepted the outcome.”

Today Angelina is happier than she’s ever been, the insider said. For the first time, she doesn’t feel dependent on men to make her happy — she has her baby.

Revealed the insider: “She says, ‘It’s the smartest decision I’ve ever made. I have no regrets — I’m not looking back.'”