The couple has two children: Zachary Jackson Levon born in 2010, and Elijah Joseph Daniel born in 2013.
John told People that he wrote his 2019 memoir, "Me," for his sons.
"I wanted my boys to know what I was like and what happened, so that when I'm not here, they can read the book and read the truth," he said. "I just want them to understand what I was like when I went through the journey I had before I had them. How they made my life complete. How they've, you know, finished the circle. And that, you know, they were the last chapter in an incredible life."