A man reliving the tragic death of his twin brother in the 9/11 terror attacks and the harrowing journey he's endured since has left The Project panel wiping away tears in an emotional interview.
Andrew Knox, 29, was one of ten Australians killed in the horror attacks in the US that changed the world forever on September 11, 2001.
The environmental architect from Adelaide had been working in New York and was in a meeting on the 103rd floor of the World Trade Centre's North Tower when one of the planes hit.
His death had a devastating impact on twin brother Stuart, who candidly opened up on his battles with PTSD, mental health issues and addiction to The Project on the 20th anniversary of 9/11, which left the panelists crying live on air.
The distressing scenes that shocked the world of the planes hitting the twin towers of the World Trade Centre are still a painful reminder of the day Stuart's life was ripped apart.
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The Project panellist were left in tears by Stuart's story, including Jan Fran (left)and Hamish MacDonald (right)
'It's horrific. It always has been. This is 20 years later,' Stuart told The Project's Hamish MacDonald as he broke down into tears.
'Just for a moment, pretend that you had a loved one and they died. And that somebody recorded that and they sat you down all the time and played it over and over again.
'And it is just replayed and replayed. It's not even around September. At any time of the year, watching news can be really horrific and it can re-traumatise.'
While it took weeks for authorities to officially confirm Andrew's death, Stuart says he knew his brother was dead the moment he found out about the terror attacks.
'I was playing darts with mates and then my ex-wife at the time came out to say she thought I better come inside and something was happening in New York,' he recalled.
Andrew Knox, 29, (pictured) was working in New York when he was killed in the 9/11 terror attacks
'There was that connection there, that if you're not a twin you don't understand.
'Just that sense of loss and something was going on. And of course there was something going on, something going on huge that was going to impact me directly.'
Stuart desperately tried put on a brave face for the first few years following Andrew's death but it eventually became too much.
He was diagnosed with complex PTSD and buried his grief through drugs and alcohol as he spiralled out of control.
'For many years I was trying to keep it together and doing it really publicly as if I was keeping it together. On the inside I wasn't,' he said.
Stuart Knox (pictured) has battled PSTD, mental health issues, alcohol and drug addiction in the 20 years since his twin brother Andrew was killed
'Every time I'd come to an anniversary I would try to numb the pain. I've been addicted to alcohol, to drugs, to things that make me feel anything other than the feelings that hurt.'
Those addictions forced Stuart to give up his job as a respected school principal.
He checked into rehab facility earlier this year, where he's still recovering and is now the most sober he's been in 20 years.
'There's a lot of emotion I didn't deal with 20 years ago,' he said.
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Share'I learnt in rehab the importance of being vulnerable. For me this year it's a fight to make sure that I don't numb that pain.'
The Project panelists were overcome with emotion after Stuart's harrowing interview aired but left awed by his courage.
'What a beautiful human being he is and you can only imagine how proud his brother would be right now,' Lisa Wilkinson said.
A visibly distressed MacDonald paid tribute to Stuart as fellow panelists Jan Fran and Tommy Little wiped away tears.
'I know it's been a huge decision actually for Stuart to tell his story,' an emotional MacDonald explained.
Stuart Knox hopes his twin brother Andrew (pictured) will be proud that he's the most sober he's ever been in 20 years
'He's been sort of really rock solid guy, fronting up over the years. And to share all of that was a really big deal for him. And I know in talking to him before we actually filmed that, it was really about honouring his brother and his memory.
'I hope you are doing OK, Stuart, because I know you knew it would be a tough weekend.'
Stuart says his teenage son Hudson, born two years after 9/11, keeps him going.
'For the last five years he's just been fighting to get his dad back,' he said.
'He saw me really broken, selling my house, living on the streets, living in my car, cheap hotels. To be able to spend time with him now is a godsend.
It's been 20 years since the Adelaide environmental architect (pictured) was killed in 9/11
Stuart described his late brother Andrew as loving but frustrating at times.
'He was an amazing person. He cared about other people. He had a huge heart. He was always fighting for the underdog.
'He wanted this world to be an amazing one and he wanted to be part of that change.'
He has vivid memories of their last phone call.
'I was lighting up a smoke and he said to me, "That's going to kill you."
He wasn't a smoker. And he was 10 minutes older than me, like the big brother thing he would always do.
Tim Watkins, an Australian in New York placed flowers at the memorial sites of each of 10 Australins killed in 9/11, including Andrew Knox
'So 20 years down the track he would probably be pretty proud now because of the fact I'm not smoking.'
As the world paused for the 9/11 anniversary, Stuart revealed he was getting well as he urged everyone take some time to pray or send positive energy to those still healing from trauma.
'I am letting go and I am moving through what I need to,' he wrote on Facebook.
'Focus on addiction being a disease and that we purposely use the word suffering in front of, because that's the truth for individuals and families.'
'The stigma (negative views by society, prejudice and discrimination) associated with substance use, addiction and mental health problems creates barriers to individuals accessing necessary care and support.'
For anyone in need of confidential support, contact The National Drug and Other Drug hotline on 1800 250 015 or Lifeline on 13 11 14.
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