“We were blessed to laugh with her, to travel with her, and to experience her infectious smile and love for a life filled with music,” Justin Timberlake wrote

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Justin Timberlake's longtime background vocalist Nicole Hurst has died. She was 39.

On Friday, Timberlake shared several photos and videos of Hurst on Instagram, to mourn the women he frequently referred to as his "sister."

Included in the slides were videos of Timberlake and Hurst on tour with the Tennessee Kids, including one celebratory backstage clip of Hurst being serenaded with "Happy Birthday."

A selfie the pair took was also in the carousel of memories, as was clips captured at moments the two called each other "bro" and "sister."

"My heart is so heavy. We lost a beautiful soul this week," the former NSYNC bandmember began in a heartfelt tribute. "Nicole lit up every room she walked into. On and off the stage she was a constant source of joy and positivity."

The Grammy winner, 40, continued, "Some things feel so unfair and we will never understand why they happen. What I do know is that we were blessed to laugh with her, to travel with her, and to experience her infectious smile and love for a life filled with music."

Justin Timberlake Nicole Hurst
Justin Timberlake and Nicole Hurst
| Credit: Justin Timberlake/instagram

"Nicole, it's not enough to say that I am going to miss you dearly. Thank you for your light. I will do my best to carry that with me. I love you, my sister. Forever family and forever a TN Kid. 💔," Timberlake finished.

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Hurst's cause of death is unknown.

The background vocalist, who has also sung with Kelly Clarkson, previously opened up about being diagnosed with breast cancer.

In August 2019, she revealed it came back after remission and spread to her brain.

"I was diagnosed with Stage 2 triple-positive breast cancer," she told ABC 13 Houston in 2015, revealing that she had been diagnosed in July 2013 ahead of the Legends of the Summer Stadium Tour tour with Timberlake and JAY-Z.

Opening up to the outlet, Hurst said, "I had four months of chemo followed by my surgery which I had a mastectomy. Even while I was on chemotherapy my tumor doubled in size."

Her cancer escalated to stage 3, but by 2015, she said was in remission.

In a candid social media post in August 2019, Hurst shared vulnerable photos of herself at the hospital and other moments in her life that brought her joy.

"These pictures aren't throwbacks from 2014, but from this year, literally from the 2nd day in January when my world was once again completely flipped upside down," she wrote at the time. "What was discovered was not a cancer recurrence, but breast cancer that somehow found it's way to my brain, forcing me to pull the emergency brake on my life and sent me immediately into whole brain radiation treatment to destroy everything that was trying to destroy me."

"We all know everybody shares their life's highlight reel, but rarely do we share the 'REAL' reel," she continued.  "The reality is, it doesn't matter how amazing your life looks, your background, net worth, or even who you sing with, life does not discriminate and can turn on you at any time!"

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Hurst told fans,  "My battle isn't over yet, and I don't know what the future holds...really none of us do. But I know by the grace of God, along with the unrelenting support from my incredible family and friends, I'm fighting this thang with everything in me."

"The last picture is a throwback to yesterday, my birthday!! And I'm celebrating every victory and soaking in the blessing of being able to celebrate another year of life, and many, MANY more to come!" the singer said. "I hope this post will inspire you to live courageously in your present moment and recognize that with its many ups and downs, life is still beautiful. 💛🎂."