John Easterling said Newton-John was "the most courageous woman I have ever known" and her caring nature "almost eclipses what is humanly possible".
The singer and actor, best known for playing Sandy in the 1978 hit film Grease opposite John Travolta, died on Monday aged 73.
Sharing news of her death on social media, Easterling said she had passed away "peacefully", surrounded by family and friends.
In a new post, shared from Newton-John's account on Wednesday, he thanked fans for "the ocean of support that has come our way".
"Our love for each other transcends our understanding," he captioned a picture of himself and his late wife.
"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."
Describing Newton-John as "the most courageous woman I've ever known", Easterling said, "At Olivia's deepest essence she was a healer using her mediums of song, of words, of touch.
"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 will power 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."
Following news of her death, famous faces across the creative industries including John Travolta, Dolly Parton, Elton John and Kylie Minogue paid tribute to Newton-John.
The cast of the current production of Grease The Musical on London's West End have dedicated the entire rest of the run to her memory and said they were honoured to "follow in her footsteps each night".
Aside from her hit role in Grease, Newton-John was also a multi-platinum selling artist, with two singles and two albums having earned certification from the Recording Industry Association of America.
She is survived by her husband as well as her daughter Chloe Lattanzi.
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