Julia Roberts Marriage Crisis Over Danny’s Nut Job Sister!

This laughing mug shot “could be the straw that broke the camel’s back” in JULIA ROBERTS' ill-fated marriage to Danny Moder, pals told The National ENQUIRER!

The movie star is fuming over the antics of her troubled sister-in-law Jyl Moder – who grinned for the camera after being busted on domestic violence charges on July 20.

“Julia was fit to be tied after the news broke,” a longtime pal told The ENQUIRER. “She’s always hated Jyl, whose drunken antics have been a constant thorn in her side during her marriage to Danny!”

Jyl, 49, has been busted three times on DUI charges!

The most recent arrest happened in Palm Desert, Calif., after Jyl allegedly battered her boyfriend after an argument.

Jyl has a serious grudge against Julia – believing Danny’s affair with the star contributed to the fatal heart attack of her mother, Patti Moder, in 2001, sources said.

Charged one source: “She even called Julia ‘the devil’ at a family wedding!”

Jyl could face four years in jail, and a possible $6,000 fine.

Meanwhile, Julia might be preparing for a split as she unloads homes in Hawaii and New York!

In April, the 47-year-old actress listed her historic island property for a whopping $30 million, and the couple’s Greenwich Village apartment is on the block for $4.5 million.