NOW IT CAN BE TOLD –the truth about Brad Pitt and Jennifer Aniston’s divorce that has been kept secret – until now!

Most fingers point at Angelina Jolie for triggering the  Aniston/ Pitt split, but The ENQUIRER has learned that it was Jen who pulled the plug on their 4 1/2-year marriage!

According to an insider, Jen and Brad – who tied the knot in a splashy Malibu wedding in July 2000 – were having problems long before he flipped for Angelina while filming the action flick Mr. & Mrs. Smith.

"Jen was champing at the bit to divorce Brad long before they announced their separation in January 2005," said an insider. "When Brad revealed the depth of his relationship with Angelina, it was painful for Jen, but she was almost relieved."

The once-tight golden couple had drifted apart due to career demands and the fallout from a miscarriage that Jen suffered about two years into the marriage, according to the source.

"After Jen lost the baby, she and Brad could never again agree on when they would have kids, and they continued to grow apart," said the insider.

In the end, Brad’s relationship with Angelina gave Jen an "out" for ending the marriage, said the source.

The couple had no prenuptial agreement, and the divorce was "pretty much a 50/50 California split," said divorce attorney Seymour Reisman, who has handled numerous high profile and celebrity divorces.

"But Jennifer is the one who wanted out, and she worked it so that Brad was portrayed as the instigator. In the end, she got the sympathy, while Brad got Angelina Jolie and the label of ‘bad guy.’"

For all the details pick up the latest ENQUIRER
CHECK out our gallery of Hollywood’s nastiest divorces HERE