Keith Duffy has said that comments reportedly made by the head of the Irish Autism Action (IAA) charity about him were "like a knife in my back".
The charity's chief executive Brian Murnane was reported as saying that while Duffy helped raise €8m for the charity he worked with for 14 years, it actually cost €7m to raise that amount.
Although Mr Murnane later denied making the comment, the former Boyzone star said he was devastated after reading media reports about it.
"To have read that, to have received the amount of emails and phone calls I got from the media after the statement was made, I'm not going to lie to you, I was sick to my stomach," he said.
"I put my family's private story out there to try and help other families against my family's better wishes at the time.
"When I read that, I thought it was a direct insult to me, it was like a knife in my back. I was devastated.
"I actually had a panic attack. I was hyperventilating because I just could not believe that there was somebody in this world that would make such a flippant comment."
During an emotional interview on the Anton Savage Show on Today FM, Duffy said he had done "absolutely nothing wrong" and had only tried to help other families who were going through the same experience as he and wife Lisa.
The couple's daughter, Mia (16), has autism but has overcome many obstacles thanks to receiving critical early intervention.
Duffy also said he never received nor expected a penny from his charity work and never took expenses.
"I cut my holidays short to make sure I was there for events for Irish Autism Action. I had police escorts from Cork to get to Dublin to make sure I was there to support events for Irish Autism Action. My family have missed me on holidays because I had to be there," he said.
"I was dedicated. I spent my life with it. I've turned down career opportunities to make sure I wasn't diluting what I was trying to achieve. I have, hand on heart, worked my arse off for years to support other families like mine."
Duffy stepped down as patron of the charity last year.
"You can't regret doing it because IAA initially was put together by parents of children with autism with the best of intentions and the State has let down the families of children with autism," he said. "Parents are pulling their hair out, they don't know what to do.
"I meet people on the street every day who know I'm involved with autism and they ask me for my help. I don't know what to say to them any more, I don't know where to send them any more."
He has now moved on and set up the Keith Duffy Foundation to raise funds for a wide range of charities.
However, he believes those affected by autism should unite and "vote in a new and fresh and vibrant and passionate committee and board of IAA members" to continue the charity's work.