Olivia Newton-John's Sister, Rona Newton-John, Dies of Brain Tumor at Age 70

Grease star remembers her "beautiful, smart, talented, funny, brave sister," who passed away on May 24

Sad news for Olivia Newton-John's family.

The Grease star's older sister, Rona Newton-John, died Friday at age 70 after battling an aggressive brain tumor she was just diagnosed with last month.

Olivia, who is a breast-cancer survivor, confirmed the news on her Facebook page Wednesday.

"My beautiful sister Rona sadly passed on May 24th in Los Angeles. It was May 25th in Australia - which was our mother Irene's birthday," she wrote.

"Rona died of a very aggressive brain tumor and mercifully suffered no pain. She was surrounded by the love of her four children - Fiona, Brett, Tottie and Emerson, and her wonderful friends," she continued. "I will miss her forever - my beautiful, smart, talented, funny, brave sister Rona."

The family has asked that in lieu of flowers, donations be made to the Olivia Newton-John Cancer and Wellness Centre, where a brain-tumor wellness program will be set up in Rona's name.