Posting to the star's official Instagram account, John Easterling has issued a touching tribute dedicated to "the most courageous woman I've ever known".
The post read, "Our love for each other transcends our understanding. Every day we expressed our gratitude for this love that could be so deep, so real, so natural. We never had to 'work' on it. We were in awe of this great mystery and accepted the experience of our love as past, present and forever.
Olivia Newton-John's husband John Easterling has issued a touching tribute to his late wife. Photo / Getty Images
"At Olivia's deepest essence she was a healer using her mediums of song, of words, of touch. She was the most courageous woman I've ever known.
"Her bandwidth for genuinely caring for people, for nature and all creatures almost eclipses what is humanely possible. It is only the grace of God that has allowed me to share the depth and passion of her being for so long.
"In her most difficult times she always had the spirit, the humour, and the willpower to move things into the light.
"Even now as her soul soars, the pain and holes in my heart are healed with the joy of her love and the light that shines forward.
"Our family deeply appreciates the vast ocean of love and support that has come our way."
Easterling and the Grease star met for the first time in the early 90s but their love story didn't begin until 15 years later when they officially started dating.
People Magazine reported the couple publicly started dating in 2007 after Easterling, a natural-health businessman who much like Newton-John believes in spirituality and holistic cures, helped the Hollywood starlet manage her cancer symptoms with medicinal marijuana.
By June 2008 the couple tied the knot in an intimate ceremony held on a mountaintop in Peru.
"Chloe Lattanzi, Olivia's daughter, sent me a beautiful message earlier today, which I played and cried again," Wilkins said on Wednesday's Today show.
"And I said to her, 'I would never do it without your permission. Would you like me to share your beautiful message with her many friends and fans on-air?'
"And she said, 'Yes, please. Tell them how much their love is helping me cope. I want to be a link for them. Give light, give thanks, gratitude. I'm holding you in my heart.'"
Richard Wilkins with Olivia Newton-John and Paul Hogan in 2018. Photo / Instagram
"Hi Richard, this is Chloe, I just saw your beautiful tribute to my mummy.
"I just wanted to hold you. I saw how much you loved her and I just want you to know she's free now and out of pain and all the family is here together.
"She's making the sun shine and the dogs are running around and smiling and the horses are galloping.
"I just want you to know that she's free from pain now and she fought so hard and I was with her every step of the way
"I just felt your love. Mummy and I both care about you, care about you so much.
Olivia Newton-John and her daughter, Chloe. Photo / Instagam
Newton-John died on Monday at age 73 at her home in California after a long battle with cancer, Easterling said in a statement on the star's social media.
The Australian singer and actress, who starred in Grease and had a series of hit songs in the 1970s and 80s, sold more than 100 million albums.
She had battled breast cancer for three decades, having previously beaten the illness twice.
Easterling said on Facebook: "Dame Olivia Newton-John (73) passed away peacefully at her ranch in Southern California this morning, surrounded by family and friends.
"We ask that everyone please respect the family's privacy during this very difficult time.
"Olivia has been a symbol of triumphs and hope for over 30 years sharing her journey with breast cancer. Her healing inspiration and pioneering experience with plant medicine continues with the Olivia Newton-John Foundation Fund, dedicated to researching plant medicine and cancer. In lieu of flowers, the family asks that any donations be made in her memory to the Olivia Newton-John Foundation Fund.
"Olivia is survived by her husband John Easterling; daughter Chloe Lattanzi; sister Sarah Newton-John; brother Toby Newton-John; nieces and nephews Tottie, Fiona and Brett Goldsmith; Emerson, Charlie, Zac, Jeremy, Randall, and Pierz Newton-John; Jude Newton-Stock, Layla Lee; Kira and Tasha Edelstein; and Brin and Valerie Hall."
One of Olivia Newton-John's Instagram posts showed her smiling while surrounded by sunflowers. Photo / Instagram @therealonj
Her Grease co-star John Travolta was the first to lead the celebrity tributes and posted a photo of the actress to his Instagram account with the caption, "My dearest Olivia, you made all of our lives so much better. Your impact was incredible. I love you so much. We will see you down the road and we will all be together again. Yours from the moment I saw you and forever! Your Danny, your John!"
From 1973-83, Newton-John was among the world's most popular entertainers.
She had 14 top 10 singles just in the US, won four Grammys, starred with Travolta in Grease and with Gene Kelly in Xanadu. The fast-stepping Travolta-Newton-John duet, You're the One That I Want, was one of the era's biggest songs and has sold more than 15 million copies.
