ENOUGH is enough!”  That’s what BARBRA STREISAND told DIANE LANE, prompting her to file for divorce from Barbra’s stepson, JOSH BROLIN.

“Barbra has always cared more for Diane than Josh,” an insider told The ENQUIRER. “She feels he’s mistreated her enough and all the love in the world wasn’t going to save her marriage. She told Diane that it was time for her to cut her losses. In the end, poor Diane finally accepted that there was nothing left to salvage. Her life with Josh was over.”

The “Unfaithful” star, 48, wed the bad-boy actor, who’s admit­ted to using heroin as a teen, in August 2004.

JUST four months later, police were called to their home on a domestic violence incident. But Diane claimed it was a mis­understanding and declined to press charges.

In 2008, Brolin was arrested in Shreveport, La., while filming the biopic “W.” Again, charges were dropped.

Sources say the last straw came when Brolin, 45, was ar­rested for public intoxication on New Year’s Day in Santa Moni­ca, Calif.

“Diane thought she could tame Josh, but their life together was a roller-coaster,” said the source.

“She never knew which Josh would come home – the kind and loving Josh or a crazy madman with a hair-trigger temper.”

At Barbra’s urging, Diane finally filed for divorce in Los Angeles County Court on Feb. 15.

“Diane and Josh love each other, but they’re a bad fit,” said the source. “It’s a very sad time for both of them.”