Credit: AKM IMAGES/Splash News Online

'Tis the season!

LeAnn Rimes and Eddie Cibrian kicked off their first holiday season as a public couple.

The country singer, 27, and the CSI: Miami star, 36, attended the Christmas tree lighting ceremony at L.A. Live in Los Angeles. Thursday. Rimes, wearing a sparkly gold mini dress, performed "White Christmas" on stage as Cibrian watched.

Rimes -- who filed for divorce from husband Dean Sheremet a week after Cibrian filed papers to end his eight-year marriage to wife Brandi Glanville in August -- said she would be celebrating Christmas "with my family at my house" and laughed when asked if she'd be preparing the holiday feast.

"I can cook, but I'm not cooking Christmas dinner!" she said.

After the tree was lit, she and Cibrian left together, hand in hand.

Although they seemed to get into the holiday spirit, their public outing came as another alleged Cibrian mistress disclosed details of their affair.

Scheana Marie told Access Hollywood Thursday that she was intimate with then-married Cibrian in 2006.

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"He would tell me and he would tell Brandi anything we wanted to hear," she said.

She said their relationship lasted for six months and that she didn't even know he was married until after they'd begun dating.

"I just wanted to believe what he was saying," she said. "I was just kind of like, ‘Don’t ask, don’t tell.’ Whatever, let’s have a great summer. When you're with me, you're with me. When you're not, we'll just do our own thing."