In a startlingly honest new interview, LeAnn Rimes admits that she has had suicidal thoughts and worried that her husband, actor Eddie Cibrian, will cheat on her.

Rimes and Cibrian met each other on the set of a Lifetime movie while they were each still married to their now-former spouses. A very public affair ensued, and the pair endured a firestorm of controversy when they divorced and then married one another. The stress from that public criticism drove Rimes to seek treatment for emotional issues last August, and she admits to Entertainment Tonight how bad things really got.

"I think any smart person would know that that is always a possibility, that you could always get that sad," she tells Nancy O'Dell when asked if she had ever contemplated suicide. "I worried that that was a possibility. I didn't think that I would ever ... I know that I would never [commit suicide]."

Rimes further details her struggles in a candid new song titled 'Borrowed,' in which she repeatedly uses the word "pathetic" to describe herself, as O'Dell points out. "Because I was," Rimes says candidly. "I couldn't get out of bed. I became this person that I never knew existed within me, and I did not like her at all."

Rimes says that because her relationship with Cibrian began with infidelity, they have both harbored thoughts that the other might cheat again. “I would be ignorant to say -- and everyone else would think I am a liar -- if I didn’t say yes, and I have [thought that] at times,” she acknowledges. “Speaking for him, I would actually say that’s creeped into his [mind]. I think we’ve been very honest and open with that to each other and our conversations about it have only made me understand how much he actually cares, as much as I do, about being faithful to each other."

Rimes is slated to release a new album titled 'Spitfire' later in 2013.

Watch LeAnn Rimes Open Up on 'Entertainment Tonight'