Jason Alexander, the first husband of Britney Spears, has backed up the claims of a woman who alleges she had sex with Casey Aldridge while his girlfriend Jamie Lynn Spears was carrying his child.

Kelli Dawson revealed that her ex-boyfriend Casey was still seeing her six months into the Zoey 101 star’s pregnancy.

And Britney’s annulled husband Jason confirms Kelli’s story to In Touch, insisting it has become common knowledge that Aldridge is two-timing Jamie Lynn, the mother of his child Maddie Briann.

He adds: "Kelli and Casey have been a couple on and off for a few years. They were a really tight couple, but I think it was hard for Kelli, having Jamie Lynn in the picture."

Should Jamie Lynn dump Casey, or stay with him for the baby’s sake? Be sure to leave your comments below.