Such was the battle the former ACT Brumbies and Wallabies prop fought primarily with himself, but partly too, cultural and societal influences.

Eight years ago he was living out a childhood dream, vice-captaining the Brumbies during their Super Rugby campaign and making his international debut for Australia.

Yet in a column written for the Sydney Morning Herald, Palmer says he was "incredibly frustrated, angry and desperately sad".

"I despised myself and the life I was living," Palmer wrote.

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"I was trapped in a false narrative and could see no way out. Most nights, I cried myself to sleep and routinely numbed myself with a heavy cocktail of opioids.

"I fantasised about disappearing, changing my name and starting my life all over again. It is not an exaggeration to say my own death felt preferable to anybody discovering I was gay."

A stint with FC Grenoble in France left Palmer in a foreign country where he couldn't speak the native language. Then waking up in a pool of vomit caused by a painkiller overdose showed he was "rapidly self-destructing". Something had to change.

He booked a flight to London, and drove to the airport recklessly while pondering slamming into a tree would help him avoid the degree of discomfort which was ahead of him.

Palmer wrote what he wanted to tell his friend upon arrival and went over it countless times on the flight. When he arrived he couldn't look him in the eye.

"I distinctly remember not being able to say a word to him until we sat down at a restaurant where I cried uncontrollably across the table for minutes before passing him the note I had written on my phone," Palmer wrote.

"I don't remember what he said after reading my message, but I do remember that he got it right. He was the first person I told that I was gay in my 25 years on the planet. Telling him removed a weight I had been carrying for as long as I could remember. I am forever grateful that he was there for me that day.

"The next morning, I had changed in a way I didn't anticipate. I hadn't realised until then, but this was the first time in my life I had truly felt free. Not long after, I decided I needed to stop playing rugby and begin the next chapter of my life."

Palmer soon returned to Canberra and has since completed a double degree in science and psychology, achieved first class Honours in neuroscience and is midway through a PhD studying cellular mechanisms of brain function.

He never felt as though he wouldn't be accepted by family and friends, but Palmer feared telling them would make him look as though he had deceived them for years prior.

Palmer wanted to be judged for what he did on the field rather than who he was during stints at the NSW Waratahs and the Brumbies, yet he never felt as though he was discriminated against in a rugby environment.

But rugby union has had its battles with such topics in recent years following the drawn-out Israel Folau saga. It was not the reason for Palmer's column, but it left him feeling a sense of responsibility.

"To me, what is more important than the damage he has caused rugby is the deep impact he has undoubtedly had on kids who looked up to him, and who struggle every day with understanding their sexuality," Palmer said.

"He will never see the impact he has had on these young people, but if he could, I doubt he could live with himself. Thankfully, from my experience in rugby, views like Israel's are the exception, not the rule.

"It was encouraging to hear a chorus of prominent voices from rugby players and officials globally that condemned his position and continue to push for a more accepting and inclusive sporting landscape."

Wallabies captain Michael Hooper says he is unsure if it will help more players privately battling their own demons to come out, but believes the column could spark a change.

"I guess that's why someone like Dan is putting that out there, his words speak loud," Hooper said.

"I feel really happy for Dan, he's a great bloke, a great Wallaby, a great rugby player and now coach."