Richard Brian / Reuters file

Singer LeAnn Rimes and her husband Eddie Cibrian in 2012.

LeAnn Rimes is ready to face the music -- her music -- after her 2009 affair with now-husband Eddie Cibrian. In a new single, "Borrowed," the star opens up about the couple's forbidden love, which developed on the set of "Northern Lights" while both were still involved with other people. (Rimes wed Dean Sheremet in 2002; Cibrian had been married to Brandi Glanville since 2001.) 

PHOTOS: LeAnn and Eddie's road to romance

"I wanna hold out, but I hold on, even though I know it's wrong," she sings. "Cause I don't want to give you back, you're the best I ever had -- but you're borrowed."

"I carried that song and that title around with me for about eight months," Rimes told "Extra" after her "X Factor" performance with Carly Rose Sonenclar on Dec. 20. "I was afraid to write it because I knew I had to be incredibly personal...When I did, it was through a lot of tears."

PHOTOS: LeAnn's bikini body

Another reason she waited so long? Cibrian. Though she told Extra her husband of a year-and-a-half is "always so supportive," she worried a little about rehashing their past.

"I actually was scared to put him in the song, because it does talk about how we both hurt each other," she explained. "There was a moment where we did have some hurt between the two of us that we had to accept and get over and move forward."

PHOTOS: Cheating scandals of 2012

Because of that, however, their marriage is much stronger. As she told "Extra," it's "made for an amazing relationship."

Related content:

• Rimes 'starting over' after rehab
• Rimes sues over taped conversations

John M. Heller / Getty Images

LeAnn Rimes in Los Angeles on Oct. 6.

LeAnn Rimes surprised us all in August when she checked into rehab for anxiety and stress a day after her 30th birthday. But if you ask the country star, her month spent in the voluntary program was a positive, restorative thing.

"I feel like I'm starting over even though I've had all these years behind me," Rimes tells Katie Couric in an interview airing later this week on "Katie" and a special edition of 20/20 called "All Access Nashville."

"How many people get to (start) over again in this day and age?" she muses.

LeAnn stuns without makeup

"People look at you and go why are you struggling?... No one can quite understand why you hurt so badly," she tells Couric.

Rimes' husband, Eddie Cibrian, has been extremely supportive of the singer-actress. But Cibrian's ex-wife, Brandi Glanville, isn't exactly getting along well with the stepmother of her and Cibrian's two sons.

"Right now it's not amazing," she told OK! magazine of her and Rimes' relationship at the "Real Housewives of Beverly Hills" premiere. "I'm just saying ... and I'll leave it at that."

Check out LeAnn's bikini bonanza!

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Chris Pizzello / AP

LeAnn Rimes and husband Eddie Cibrian.

This has been quite the week for LeAnn Rimes. After celebrating her 30th birthday Tuesday and promptly checking into rehab the next day, the country crooner filed a lawsuit Thursday against two women who allegedly "secretly" recorded one of her telephone conversations.

Perhaps this had something to do with Rimes' "stress and anxiety" issues.

LeAnn Rimes tweets sexy bikini pic after root canal

Eddie Cibrian's wife filed the lawsuit in Los Angeles Superior Court against Kimberly and Lexi Smiley and other individuals (whose names she has yet to uncover), for invasion of privacy, claiming they have orchestrated a "campaign of harassment" against her since she began dating her "Good Deeds" star hubby. 

According to the complaint, Rimes alleges that the individuals secretly recorded a private telephone conversation without her knowledge or consent and then "conspired to spitefully ensure that out of context excepts of that recording would be disseminated to the public on various websites ... in an effort to portray Ms. Rimes in an egregious false and negative light and cause her emotional distress." 

The suit states Rimes has put up with their "campaign of harassment in the hope they would tire of posting false and defamatory statements," but the "outrageous conduct" has only been escalating and Rimes "can no longer merely hope" the behavior will stop.

Rimes said she has been the target of an "increasingly aggressive internet campaign by supporters of her husband Eddie Cibrian's first wife, 'Real Housewives of Beverly Hills' star Brandi Glanville." Rimes believes the individuals she is suing are behind this campaign which started when she began dating Cibrian. 

View the documents

In Spring 2012, a friend of the defendants encouraged Rimes to talk to the Smileys in an attempt to end the negative Internet activity. Rimes spoke to them on the phone, but did not know she was being taped. 

The recording was later posted on "hate" blogs such as Celebitchy.com and CrazyDaysAndNights.com, among others. Rimes states the posting has "harmed her reputation and personal relationships and have caused her emotional distress."

Take a look at these celeb court appearances!

Rimes is asking for an injunction against the individuals to prevent them from disseminating the tape, as well as compensatory, punitive and other damages. 

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• LeAnn Rimes enters treatment for anxiety, stress

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Fred Prouser / Reuters

LeAnn Rimes and Eddie Cibrian.

Everybody feels stress, but LeAnn Rimes has now entered treatment to deal with it, according to People magazine. 

As the country singer's rep told the magazine, "LeAnn has voluntarily entered a 30 day in-patient treatment facility to cope with anxiety and stress. While there will be speculation regarding her treatment, she is simply there to learn and develop coping mechanisms. While privacy isn't expected, it's certainly appreciated."

Rimes checked in on Wednesday, and she told the magazine she wants to emerge with skills she can use in her daily life. 

"This is just a time for me to emotionally check out for a second and take care of myself and come back in 30 days as the best 30-year-old woman I can be," she said.

Her husband, actor Eddie Cibrian, offered full support. "My wife is the most remarkable and courageous woman I know," he said. "I am so proud of her for having the strength to finally take some time for herself. I will be with her every step of the way."

Rimes intends to continue promoting her newest album, "Spitfire" and performing in a fall tour as she takes breaks from treatment. 

"The facility has granted her permission to keep her weekend tour obligations, as LeAnn doesn't want to disappoint her fans," said her rep. "She will report back after each weekend."

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