Jon Gosselin is down in the dumps after a judge denied his request to prevent his family from going Down Under.

Radar Online reports the former reality star, 33, argued to keep the kids in the U.S. during a secret closed-door hearing at Berks County Court in Pennsylvania earlier this month. But because the trip was work-related (the children are filming scenes for TLC's Kate Plus Eight), the judge dismissed Jon's request.

"Kate told Jon about the trip, and when he did not agree it was decided that the judge should intervene and the ruling went in her favor," a source explains. "It was another slap in the face for Jon because he did not want the kids to go to Australia."

With the judge's permission, Kate, 35, arrived at the Brisbane Airport in Australia Tuesday with 10-year-old twins Cara and Maddy and 6-year-old sextuplets Aaden, Alexis, Collin, Hannah, Joel and  Leah.

"Jon is trying to put a brave face on it and has explained the situation to his own family and friends, but obviously not being with his kids for the New Year is a big disappointment for him," an insider says. "But they all respect him for trying to stand-up to Kate and for fighting for what he thinks is right for his kids too."