In a sweet tribute to his late wife Kelly Preston, John Travolta shared their throwback wedding picture to celebrate what would have been the actress's 58th birthday.

John Travolta took to his Instagram account on Tuesday to wish a happy birthday to his late wife Kelly Preston. "Happy Birthday hon!" he wrote alongside a collage of a photo from his mom Helen Cecilia Burke and dad Salvatore Travolta's wedding day next to a snap from his and Kelly's wedding that took place 29 years ago.

"I found this photo of my mom and dad's wedding. It was nice to see ours alongside theirs. All my love, John," the 66-year-old wrote in a heartbreaking tribute to his wife who passed away in July this year after a two-year-long battle with cancer.

Travolta and Preston began dating in 1989 after meeting on the sets of "The Experts." The "Grease" star proposed to the actress on New Year's Eve 1991 at the Palace Hotel in Gstaad, Switzerland. The couple said their vows twice, first on Sep. 5, 1991, when Kelly was two months pregnant with their first child, Jett, and then in Daytona Beach in Florida on Sep. 12.

Travolta and Preston welcomed three children together, but their first son Jett died aged 16 after suffering a seizure in January 2009. They are also parents to daughter Ella, 20, and son Benjamin, nine.

Travolta's friend and "Grease" co-star Olivia Newton-John recently opened up about how he is dealing with the loss of the love of his life. "I just know that she was a radiant, beautiful light in the world," she said about Preston while speaking to Sandra Vergara on Tuesday's episode of People (the TV Show!). The 72-year-old, who has had her own battles with breast cancer, was promoting the launch of the Olivia Newton-John Foundation, which will fund the discovery of kinder therapies for cancer.

John Travolta and Kelly Preston
Actress Kelly Preston and actor John Travolta pose at the Academy of Motion Picture Arts and Sciences' 2011 Governors Awards in Hollywood, California.

Newton-John added that Travolta is doing "as well as it can be expected when you just lost your love, your wife and the mother of your children." She also said that Preston's death "really strengthened" her resolve to form the cancer foundation, since she has "lost way too many friends to cancer."