Maybe what goes around truly does come around.

LeAnn Rimes, who was once a talented singer but in recent years has stayed in the spotlight thanks mainly to her man-stealing ways, recently entered an inpatient treatment facility for "anxiety" issues -- and it seems that stress was largely fueled by worries that the man she swiped may now be cheating on her.

When Rimes met Eddie Cibrian three years ago on the set of their craptastic TV movie 'Northern Lights,' both of them were married to other people. One very public affair and two divorces later, they tied the knot in April of last year.

Since the whole mess started, Rimes has posted a lot of photos of herself and Cibrian practically copulating for the camera, and then had the temerity to be shocked -- shocked! -- when people called her out for acting like a trashy guest on 'Jerry Springer' and expressed sympathy for Cibrian's ex, 'Real Housewives of Beverly Hills' star Brandi Glanville.

But hey, even home-wrecking pop stars have feelings, you guys, because a friend of Rimes' tells Us Weekly that all that self-induced "cyberbullying" has taken a toll, sending her into a "downward spiral" helped along by an "all-consuming obsession" with Cibrian's "wandering eye."

"LeAnn has had major insecurity issues since she first got together with Eddie," the source said. "She's been stressed about always being called a home-wrecker and also worried that Eddie is cheating on her."

Rimes' rep says she admitted herself into a 30-day inpatient treatment facility for anxiety "to learn and develop coping mechanisms." And maybe learn a little something about the laws of karma.

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