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(Yahoo!) - LeAnn Rimes sang about her own cheating heart on Tuesday night during an appearance on “The Tonight Show With Jay Leno.” The country star performed “Borrowed,” about her affair with now-husband Eddie Cibrian when they were both married to other people. The song is the first single off her upcoming album Spitfire. “I wanna hold out, but I hold on, even though I know it’s wrong,” Rimes sang. “Cause I don’t want to give you back, you’re the best I ever had … but you’re borrowed."

After the performance, Rimes explained to Leno that the track, which she first debuted in concert earlier this year, “is about ... the situation. I did go through a very public affair with Eddie, who is now my wonderful husband. The song looks into the darker moments of things. People think that it was done with complete abandonment. It wasn't … I call myself pathetic in the song because at that moment I was pathetic. The chorus is, ‘I don't want to give you back.’ It's a very intimate look into a very rough moment of my life.”

As of Wednesday morning, Rimes’ biggest critic, Cibrian’s ex-wife Brandi Glanville, hadn’t yet made a comment – either on Twitter or to omg! – about the singer’s performance. But perhaps it was because she was already asleep by the time the show aired. One of her last tweets, which she sent around 10 p.m. PT, said that she was going to sleep early after going out to dinner with her two sons with Cibrian, Mason, 9, and Jake, 5.

READ MORE: Yahoo!