Olivia Newton-John has reacted to the death of Kelly Preston, wife of the singer's former "Grease" co-star John Travolta.

Preston died at the age 57 on Sunday after a private battle with breast cancer. Also an actress, she is survived by Travolta, 66, and their two surviving children Ella, 20, and Benjamin 9.

Following the shocking news, Newton-John, 71, expressed her grief over the loss.

KELLY PRESTON, ACTRESS IN 'JERRY MAGUIRE,' DEAD AT 57

"Kelly was a radiant, warm and gentle spirit -- a loving, devoted wife, mother and sweet friend," the "Physical" singer said in the statement to Entertainment Tonight. "My heart breaks for John, Ella and Ben. No words can express my sorrow for her family. Kelly's light shines on in her beautiful children.”

Travolta confirmed the news in an Instagram post on Sunday, sharing a photo of his late wife.

"It is with a very heavy heart that I inform you that my beautiful wife Kelly has lost her two-year battle with breast cancer. She fought a courageous fight with the love and support of so many," he announced. "My family and I will forever be grateful to her doctors and nurses at MD Anderson Cancer Center, all the medical centers that have helped, as well as her many friends and loved ones who have been by her side."

KELLY PRESTON'S DAUGHTER, ELLA, PAYS TRIBUTE TO 'COURAGEOUS' MOTHER FOLLOWING HER DEATH

The actor continued: "Kelly’s love and life will always be remembered. I will be taking some time to be there for my children who have lost their mother, so forgive me in advance if you don’t hear from us for a while. But please know that I will feel your outpouring of love in the weeks and months ahead as we heal."

Left to right: Olivia Newton-John, John Travolta and Kelly Preston. Preston died on Sunday after a battle with breast cancer

Left to right: Olivia Newton-John, John Travolta and Kelly Preston. Preston died on Sunday after a battle with breast cancer (Getty)

The family also suffered tragedy in 2009, when Travolta and Preston's son Jett died at the age of 16.

A rep for the family told People magazine that Preston chose to keep her breast cancer fight out of the public spotlight.

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"Choosing to keep her fight private, she had been undergoing medical treatment for some time, supported by her closest family and friends," the statement explained. "She was a bright, beautiful and loving soul who cared deeply about others and who brought life to everything she touched. Her family asks for your understanding of their need for privacy at this time."