Inside John McCain's Love Story with Wife Cindy: 'He Is My Hero and I Love Him with All My Heart'

Sen. John McCain’s wife of 37 years, Cindy, flicked at their nearly 40-year love story in an emotional Instagram Wednesday night, just hours after the Arizona Republican revealed his brain cancer diagnosis.

Sharing a smiling photo of the couple on their wedding day in 1980, Cindy called her husband her “hero” and “the toughest person I know.”

“I love him with all my heart,” the 67-year-old also wrote.

The couple’s love story, however, had a complicated start.

When McCain met glamorous, 25-year-old heiress Cindy Lou Hensley at a cocktail party in Hawaii in 1979 he “by all accounts, fell instantly in love,” The Washington Post reported in 2008. He pursued her for months, flying back and forth from Washington to Arizona to see her.

There was just one problem: McCain, then a 43-year-old naval attache, was still married to his first wife, former model Carol Shepp, with whom he shares three children (including a daughter, Sidney, now 50, and Carol’s two sons from a previous marriage, Douglas, 57, and Andrew, 55, whom McCain adopted).

McCain’s marriage had already been on the rocks, and he soon filed for divorce from Carol. He married Cindy on May 17, 1980, just six weeks after his divorce from Carol was officially dissolved, according to the Post.

McCain described how he instantly fell for Cindy during an interview with Larry King in 2002, amid the senator’s first presidential campaign.

“Schmaltzy as it sounds, it was love at first sight,” he said. He added that Cindy had “done very well” campaigning for him, but that “primarily, she’s been a mother” to their “four wonderful children,” Meghan McCain, now 32, John Sidney McCain IV, 31, James McCain, 29, and Bridget McCain, 25, whom the couple adopted from Bangladesh when she was three months old.

“When you have four children … you’ve got your hands full,” he said at the time.

Cindy was similarly smitten when she met McCain. In 2008 she confessed that both she and her future husband lied about their ages at first so as not to turn each other off.

“He made himself younger, and I made myself older, of course,” Cindy once told Ryan Seacrest on his KIIS-FM radio show.

The truth about their 17-year age gap came out just before the couple’s 1980 wedding.

“In Arizona when you apply for a marriage license, it’s published in the newspaper,” she told Seacrest. “Of course when they published the application, we both found out together our true ages.”

“It didn’t matter anyway,” she continued. “I felt like he wouldn’t be interested in someone as young as me – and he felt I wouldn’t be interested in someone that was older, like he was. So it was for true love that we did it. And it’s been a funny joke for our kids ever since.”

When the couple wed, McCain was still a Navy captain but soon decided to get into politics.

“I thought I was going to have the life of a Navy wife, and won’t that be exciting?” Cindy said in a 2008 PEOPLE cover story on then-presidential candidate McCain and his family. “But life hands you different things.”

Together, the couple decided that Cindy would raise their children in Arizona, her home state, while McCain would come home from Washington on weekends and holidays. “We wanted them to have a well-rounded life, and we gave them that out West,” said Cindy.

Despite the distance, the McCains have always been close-knit, with the patriarch enjoying a playful relationship with his children.

“That’s just the way John is: The more he teases you, the more he loves you,” Cindy explained at the time.

Friend Betsey Bayless told PEOPLE in 2008 that even though the McCains had never been particularly affectionate in public, it was obvious to those who knew them well that “the bond between them is just incredible.”

Other friends shared that the couple were sweet and tender with each other in private, noting that Cindy often combed her husband’s hair because he can’t reach above his shoulders due to war injuries.

McCain has helped his wife through troubled times as well. In the early ’90s, after back surgery, Cindy became addicted to painkillers, some of which she swiped from the medical charity she founded.

She hid her addiction from her husband, who only found out after her family confronted her.

“I kept it from him because I didn’t want to let him down,” said Cindy, who recalled being comforted by her husband after he rushed home from Washington once he found out.

“He sat down next to me and said, ‘You should come to me first with whatever it is — I love you, I’m here for you, I will get through this with you,’” she says. “And he did.”