Matt Stapleton on Wife Kelli: 'I Still Love Her, but I'll Never Forgive Her'
07/01/2014 AT 04:00 PM EDT
"It should be black and white – it should be easy to deal with," he says in an exclusive interview with PEOPLE. "The reality is, it's not."
Prior to his scheduled appearance Tuesday in a pretrial hearing, Matt broke his long silence to describe the "amazing" rebound and challenges still faced by his 15-year-old daughter Isabelle – nicknamed Issy – since the Sept. 3, 2013, failed murder-suicide attempt by his wife, Kelli, whose trial begins July 16.
Kelli, 46, has pleaded not guilty, and faces a maximum life sentence.
After she and her daughter were found unconscious from carbon monoxide poisoning when Kelli allegedly lit two charcoal grills in a closed van, Kelli – a high-profile blogger on autism and, with Matt, a determined advocate for her daughter's care – said that after years of Isabelle's physical abuse targeting Kelli and other family members, she "thought this would be the best solution … if Issy and her went to heaven," according to police quoting from court documents.
Says Matt, 42, a high school principal who lives in Elberta, Michigan: "Who knows when and if she made a decision to do what she did? At whatever point, she felt like that was her only option. And I think there are other parents that fall in that category."
But he is not offering Kelli an excuse. "This is not an okay act," he says. "I still love her, but I'll never forgive her."
Instead he is speaking out, he says, to advocate for more help so that other families can not only assist their children who have autism, but better handle their own stress as well.
"I couldn't have made it through this tragic event without the support of my family, friends and an incredibly close community," he says. "I hope this traumatic event will prompt a call to action."
For more about Matt Stapleton, his daughter Issy and their life today, pick up this week's issue of PEOPLE, on newsstands Friday