EXCLUSIVE: Keith Urban's Goodbye Remorse Exposed — How Country Crooner is Drowning in Second Thoughts as Ex Nicole Kidman Moves On

A regretful Keith Urban is having second thoughts about his split from Nicole Kidman, his wife of 19 years, especially as she's been looking incredibly sexy and youthful at recent red-carpet appearances, RadarOnline.com can reveal.

With eligible guys lining up to date the Babygirl star, the country crooner, 58, is lamenting the breakup, which insiders alleged was the result of his wandering eye.

"Nicole's been having a real moment, she looks better than she has in years and it hasn't gone unnoticed by Keith," said an insider. "Seeing her out there glowing, looking better than ever, it has really hit home that she's not slowing down."

As for the 58-year-old Oscar winner, she's clearly putting a lot of care into her looks, shared the source.

"It's nothing over the top – she's taking that very controlled, subtle approach she's always had," the insider said. "She did a really intense laser treatment to smooth and tighten her skin and some other noninvasive stuff."

Although Kidman has a reputation as a nip-tuck addict, the insider insists that's not the case.

"She's actually a lot more conservative with plastic surgery and all that stuff than people give her credit for," said the source.

But whatever she's done recently has worked wonders, added the source.

"She looks like a million bucks and she's projecting so much confidence," the insider said. "There's this sense that she's back on the market in a big way and it won't take long before someone snaps her up."

Already, she and her Scarpetta costar Simon Baker, 56, have sparked romance rumors after the two were spotted holding hands and flirting at the Scarpetta premiere, where Kidman told a reporter the chemistry between her and her fellow Aussie "just vibrates."