03/16/2012 at 10:00 AM EDT
In the months following his daughter JonBenét's brutal murder
, John Ramsey contemplated ending it all.
"I wanted to escape from the pain," Ramsey – the author of a new memoir, The Other Side of Suffering
, which recounts the aftermath of that fateful day in December 1996, when he found the 6-year-old's lifeless body in the basement of his and wife Patsy's Boulder, Colo., home – tells PEOPLE.
Long the targets of the Boulder Police Department's investigation, Ramsey, 68, says he and Patsy, who died of ovarian cancer in 2006, were prepared to go to jail, signing over custody of JonBenét's older brother Burke to a relative.
"Patsy joked, 'Can I have stripes that run vertical? Horizontal are going to make me look fat,' " he recalls.
The case proved equally hard for young Burke, who was only 9 when his sister was killed. He, too, featured at the center of the investigation.
Now 25, the "quiet" Purdue University grad "has certainly matured as a young man," says his father. "He's got a 401K plan, an IRA [and] "a girlfriend."
John, who was formally cleared of having any involvement in JonBenét's death by the Boulder County district attorney in 2008, has a new love in his life, as well.
After briefly dating Beth Twitty
, Natalee Holloway's mother – "a wonderful woman," Ramsey says – he met Las Vegas-based fashion designer Jan Rousseau, 54, a twice-divorced mother of two grown daughters.
Ramsey and Rousseau wed last July
in an intimate 60-guest ceremony at an estate in Charlevoix, Mich., where they have a home. (They also spend time in Nevada.)
Finding love again, along with writing the book, has further helped his healing, says Ramsey, though he still "would like to know" who killed his daughter.
"Everybody has a burden, and I wanted to tell people it doesn't last forever," he says. "There is light at the end of the tunnel."