(WJW) – John Easterling is paying tribute to his late wife, Olivia Newton-John, who died at the age of 73 Monday morning.

Easterling took to Instagram on Wednesday, expressing that their love for each other was “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,” he said in the post.

The Grammy award-winning star was reportedly surrounded by those she loved most at her California home when she died. She had been open about her fight against breast cancer for years.

“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,” Easterling said in the post. “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 humor and the willpower to move things into the light.”

Easterling said their family deeply appreciates the amount of love and support they’ve received at this time and over the years.

“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,” he said.

The family also asked that any donations be made in her memory to the Olivia Newton-John Foundation Fund (ONJFoundationFund.org).

Known as Sandy to a whole generation of “Grease” fans, Newton-John was born in Britain but raised in Australia. She had five No. 1 hits over her storied music career including “Physical.”

Newton-John’s “Grease” co-star John Travolta also took to Instagram to honor her life.