Julia Roberts threw a party in Mexico after her boyfriend’s divorce — but was shattered when his family didn’t show up for the big bash!

The “Pretty Woman” tried to put on a brave face as she and cameraman Danny Moder went ahead with the celebration in the Mexican resort town of Cabo San Lucas.

But Julia was still badly stung by the snub from members of the Moder family, who felt it was “crass” for Julia and Danny to celebrate after his divorce from makeup artist wife Vera.

“Julia was clearly shattered that Danny’s sisters and his film exec dad Mike Moder wouldn’t come to Cabo San Lucas with them for a big fiesta in late May,” a source disclosed.

“The whole point of the party was so Julia could patch things up with Danny’s family and start planning their wedding ceremony.

“She was going to fly everyone down on a private jet, put them all up in the nicest accommodations she could find and throw a big dinner.

“But the Moder family thought it was crass for Julia and Danny to celebrate after his divorce. At this point, Julia feels she just can’t get a break with Danny’s family. Every time she feels like she’s won them over, they snub her.

“It’s been the most difficult part of her relationship with Danny. He’s so close to his father and sisters. They have a huge influence on how he conducts his life.

“And Julia wants desperately to have the Moders in her corner.”

An insider declared: “Julia is devastated!

“She’s worked so hard to ingratiate herself with Danny’s family, but they still feel Julia’s a home-wrecker who busted up Danny’s marriage.

“The family is still close to Vera, and the last thing they wanted to do was celebrate after Danny’s divorce from her.

“They feel Danny’s romance with Julia is all wrong, and resent her for not only breaking up his marriage but being nasty to Vera as well.”

Danny and Julia tried to make the best of the situation in Cabo, but “Julia was sullen-faced the whole time,” said the insider.

For the first time Danny is talking about marrying Julia whether his family comes to the ceremony or not, the insider added.

“It’s coming down to Danny having to take sides — is he with his family or Julia?

“Julia has cried on his shoulder a lot, and he’s told her how his marriage to Vera was already over by the time they hooked up last year.

“He says he and Julia have decided to make a few more efforts at reconciling, before they head out on their own and say ‘forget it’ to the family.

“But it’s clear he’s made his choice in the matter — it’s Julia all the way!”