Keith Urban Fuming at Being 'Cast Aside' by Children as Insiders Reveal Daughter Sunday Rose's Met Gala Debut with Ex-Wife Nicole Kidman 'Hurt' Singer

Keith Urban was left fuming after daughter Sunday Rose appeared to figuratively pledge her allegiance to mom Nicole Kidman in the most public way possible at the Met Gala, according to new claims.

RadarOnline.com can reveal insiders close to the singer believe Sunday Rose's surprise appearance at the A-list fashion event was a pointed signal to the country star, 58, that his family was "icing him out."

The source added: "He feels disrespected and cast aside by his own daughter."

The Met Gala showing comes after Sunday Rose, 17, recently unfollowed her dad on Instagram, amid reports sister Faith Margaret, 15, was drifting away too.

The insider told Daily Mail: "I know that the Met Gala scene was very hurtful. It was a public statement for Sunday. She's definitely on her mom's side. This public appearance is 100 percent a message of who she's chosen."

The source added that the Met Gala moment was "obvious" to Urban, though he still would have loved to be part of it, admitting he was "feeling FOMO (fear of missing out)."

Urban and Kidman's daughter have seemingly sided with their mom following their divorce due to the singer's romantic links with Nashville musicians.

Both Sunday Rrse and Faith Margaret are reportedly upset he has chosen to move on so quickly — and with women much younger than him.

Last month, it was reported that the teens were refusing to meet their father's rumored new girlfriend Karley Scott Collins, 26.

The apparent cold shoulder has only fueled whispers that the girls are increasingly aligned with their mother in the aftermath of the split.

A separate source said: "(The girls] are completely team Nicole and, right now, Keith is the bad guy. He loves those girls, but they are so angry at him and they're blaming him."

RadarOnline.com recently told how Urban is plotting revenge against his ex-wife by ramping up plans to tell his side of the story in a bombshell interview that would be the Scarpetta star's possible nightmare.

The singer was also upset Kidman, 58, failed to acknowledge him in a recent magazine chat.

"Keith was really taken aback when he saw the interview because it felt like Nicole had gone out of her way to pretend he doesn't exist anymore," a source told RadarOnline.com. "She talked about her family and her life, but never mentioned him – it feels as though she just wants to erase him."

The Oscar winner, who filed for divorce last September, soon after rumors began swirling that Urban was wooing guitarist Maggie Baugh, 25.

The pair reached a settlement on Jan. 6, with Kidman being granted primary custody.

In the interview, Kidman was asked if she was doing all right in the wake of the split. "I am, because I'm always going to be moving toward what's good," was her icy response

"Keith has tried very hard to keep things between them amicable," said an insider. "He would have loved to do the whole conscious-uncoupling thing, but Nicole wouldn't hear of it."

He claims that when he told her he wasn't happy in their marriage and wanted a divorce, "it was like a gate slammed shut and he was suddenly dead to her," said the insider. "He was hoping it would get better after the shock wore off. But clearly, she's not done punishing him."

Kidman is even considering moving back to her native Australia with their daughters.

"It feels very unfair to him because he's taken the high road and let this whole narrative about him being the villain circulate without correcting it and he gets no thanks," said the insider. "It won't shock anyone if he decides to do a tell-all to set the record straight. She's being so cold, what does he have to lose?"