LeAnn Rimes

LeAnn Rimes, 26, is having an affair with her TV movie costar Eddie Cibrian, 35, reports the upcoming issue of Us Weekly. The singer-actress, who shot to stardom at age 13 for her rendition of "Blue," married backup dancer Dean Sheremet when she was 19. The pair have no children. Rimes and Cibrian costar in the upcoming Lifetime Nora Roberts' adaptation "Northern Lights," the trailer of which is below.

The new Us Weekly features pictures taken from a video security camera that show the two holding hands and kissing on a romantic dinner date at Mosun and Club M in Laguna Beach, California on March 7. Additionally, Us Weekly reports that the new couple met for a three-hour tryst at the Malibu Beach Inn on March 14. "From the moment we rehearsed, LeAnn and Eddie honestly developed a really strong bond and a warm relationship," director Mike Robe told Us prior to news of the affair.

Rimes married Sheremet seven years ago -- when she was just 19 and he was 21. Cibrian tied the knot with model Brandi Glanville in 2001; they have two sons, ages 5 and 23 months. A rep for Rimes tells Us: "We do not comment on our clients' personal lives." For more details on Rimes' shocking affair with her costar, the steps she took to save her marriage to Sheremet and why she strayed, pick up the newest issue of Us Weekly.