Denise Richards and Richie Sambora split following argument in Nashville

Last week, Richie Sambora was scheduled to appear at the CMT Music Awards with on-and-off girlfriend Denise Richards, but he pulled out at the last minute and flew back to Los Angeles from Nashville. Though he told producers he had to attend to 14-year-old daughter Ava, he later claimed to be sick. Now insiders tell Celebuzz that he actually left following a split with Richards, who did attend the awards show.

"It's over," says a source. "They had an epic argument in Nashville and Denise told Richie she couldn't continue the relationship any longer."

Last week, Richards' ex-husband Charlie Sheen -- the father of her two daughters -- told Rolling Stone magazine that he still wants to sleep with Richards. "She still looks f**king great," he said. "Do I want to? Yeah! Does she? Don't know."

Richards will appear in Sheen's new television show, "Anger Management," which premieres on FX on June 28 at 9 p.m.