via AP / Retna Ltd. 1 / 7
via AP / Retna Ltd. 1 / 7

After a tumultuous love affair that ended both their marriages, there just might be a happy ending for LeAnn Rimes and Eddie Cibrian. The couple announced on Monday that they are engaged.

"Yes, they were engaged over the holidays and are very happy," Rimes's rep told PEOPLE exclusively.

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A source told the magazine that the couple, who spent Christmas at home in Los Angeles, "had family and close friends in town who helped them celebrate."

Rimes, 28, was spotted in Malibu with Cibrian, 37, wearing a platinum ring featuring a 5-carat oval diamond set in rose gold fleur-de-lis connected to the band, according to a source.

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"The couple wanted an antique feel, but a new ring," says the source, who adds that Rimes and Cibrian designed the ring together with the actor's childhood friend Brent Polacheck at Polacheck Jewelers.

Engagement rumors kicked into high gear in November when Rimes posted a picture of Cibrian on bended knee to Twitter, later assuring that there was no impending wedding. but today, Rimes posted a celebratory message to her Twitter followers.

"Thank you for all your well wishes!! We are extremely excited and look forward to a beautiful future. It's been an incredible last few days, I was shocked!!! We are blessed, our families are so happy and our lives are filled with love."

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She updated again a few minutes later, "It was nice to have our little secret for us, our families and friend's a few days! So excited to now share the wonderful news with our fans ... So funny, my dear publicist is the same rep for Natalie Portman and me. So much for his vacation lol!!! Love you Rhett!!!!!"

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Rimes and Cibrian met while filming the Lifetime original movie "Northern Lights" when they were both married to other people.