The Blue hitmaker and former Csi: Miami star Cibrian were both married to other people when they met and fell in love on the set of a Tv movie in 2009, and they subsequently left their partners to be together.
Rimes opened up about the cheating scandal in a candid new chat with E! network host Giuliana Rancic, but she struggled to keep her emotions under control as the presenter tried to understand why they decided to embark on their affair, asking, "Why act on it, when you're both married and you both have families?"
The singer insisted the decision was a heartbreaking one to make for both parties, but claimed they simply couldn't fight the chemistry between them.
In the taped interview, which airs in America on Sunday night (09Dec12), she said, "I never, ever in my heart want to hurt anyone. But... I don't think anything can separate anything that's super-connected. You might have had so many wonderful things with each other's spouses in your relationships, but something along the way broke that. You can't break what's broken already."
Rimes then began to cry as she insisted, "No one, because this is Eddie and my personal conversation, will ever understand how much thought and hurt, even towards each other, were put into our decision."
The star divorced dancer Dean Sheremet in 2009, while Cibrian left the mother of his two sons, Brandi Glanville, to be with Rimes.
The couple wed last year (11), but the singer has endured a rocky relationship with Glanville as they attempt to co-parent Cibrian's kids.