Former Westlife star Mark Feehily has revealed how he is still haunted by the bullying he suffered at school over his weight.
But the 31-year-old has said that his later global success with Westlife is proof a bad childhood experience can be overcome.
Interviewed by clinical psychologist and Irish Independent columnist David Coleman for new three-part RTE series 'Bullyproof', Feehily recounts the long-term damage done by his tormenters.
"Some of the more intense moments are still with me, very much, in terms of the physical attacks and stuff like that.
"There were times at school when I got attacked from behind or whatever and there's times when I'd be walking on the street to this day and I'll have flashbacks and have little moments of panic attacks," said Feehily.
The ex-boyband star believes that his lack of self-confidence as a teenager didn't help.
"If loads of people pick out things about you, whether it's being chubby or whatever, your own image of yourself becomes 'oh I'm just the fat guy in the class' and nobody wants to be the fat guy in the class, let's face it. It just kind of eats away at you," said Feehily, who has been working on his own musical projects as a songwriter and producer.
But pop stars can find themselves bullied too as the singer, who revealed he was gay in 2007, went on to suffer years of abuse on Twitter.
He said: "I'm not talking about people saying your music is crap.
"I'm talking about proper abuse. I can't go into what they said but some of the things that have been said to me on Twitter, if someone walked up to me on the street and said them to me . . . they would be in jail."
In the 'Bullyproof' series, host Mr Coleman offers therapeutic support to a number of teens and pre-teens, and their families, who have been affected by bullying -- either as a target or as a bully.
As part of the series, Mr Coleman met youngsters who have suffered at the hands of bullies and begins the process of helping them rebuild their shattered self-esteem.
He said one of the aims of the series is to enable people understand that bullying does not have to be tolerated in silence.
Mr Coleman said: "If you ignore bullying it doesn't go away."
He points out that bullying is not a form of "toughening up" that children need to pass through as some form of character development, but rather it is an indication that adults are not in charge.