Jimmy Kimmel is famous for his boyish humor and for playing pranks on guests on his popular late-night talk show, Jimmy Kimmel Live! But the star was as serious as could be when he updated fans on his son Billy’s health on May 28 after the 7-year-old underwent open heart surgery. “This weekend, our boy Billy had his third (of three, we hope) open heart surgery. We went into this experience with a lot of optimism and nearly as much fear and came out with a new valve inside a happy, healthy kid,” Jimmy wrote on Instagram alongside a sweet photo of Billy smiling from a hospital bed. “Billy, you are the toughest (and funniest) 7-year-old we know.”

It’s been a lifelong battle for the boy. In 2017, shortly after Billy’s birth, Jimmy revealed he had been born with tetralogy of Fallot with pulmonary atresia. Since then, it’s been an emotional journey for the comedian and his wife of 10 years, Molly McNearney, 46. (The 56-year-old and the TV writer and producer are also parents to Jane, 9; he shares Katie, 32, and Kevin, 30, with his first wife, Gina Maddy.) “Billy’s heart defect has been a nightmare for Jimmy,” a source exclusively tells Closer, noting that the ordeal has given Jimmy and his wife a new perspective. “They know that life is precious,” adds the source, “and that all that matters is that Billy’s OK.”

As Jimmy juggles his own emotions, he and Molly are doing their best to protect Billy, who underwent his first open heart surgery when he was just 3 days old and his second in December 2017. “My problems and my worries shouldn’t ​​be his problems or his worries,” the late-night host has said of shielding his son. “I think he’s going to have enough to worry about growing up with this questionable heart in his body, and I just want him to worry about hitting a home run in Little League.” The source says they explained what’s going on to Billy in terms a child would understand so as not to frighten him or worry him. “They don’t ever want him to feel that way.”

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Billy and Jane are Jimmy’s second chance at fatherhood, something he feels fortunate about. While he’s close to his adult kids — Katie is an artist, while Kevin works as a production assistant in the entertainment industry — life was different when they were young. Struggling to make a name for himself in show business, he couldn’t provide for them in the same way he can now. Often he was absent or making the family relocate for a job. “I didn’t make any money when I was in radio,” Jimmy has admitted, “and I got fired a lot. It wasn’t easy.”

Jimmy Kimmel Has Become an Advocate For Affordable Health Care

Perhaps that’s why he’s become a vocal proponent of affordable health care. “No parent should ever have to decide if they can save their child’s life,” he said through tears during a 2017 episode of Jimmy Kimmel Live! The four-time Academy Awards host knows not everyone has access to the medical care Billy has received — he’s personally thanked the doctors and nurses by name who have helped them over the years on his talk show and on social media, asking followers for donations to children’s hospitals. The source says he’ll continue to use his platform for good. “Jimmy and Molly feel so blessed to have such wonderful doctors and nurses assisting them,” says the source. “He’s seen firsthand how important quality healthcare is.”