The first British rugby worldwide to come out, Thomas told the paper that blackmailers had threatened to reveal his diagnosis.
The Duke of Cambridge called him "courageous as ever", global referee Nigel Owens said Thomas was "brave as ever" and Kelly Holmes called him a "legend". In his statement he shares: Hello, I'm Gareth Thomas and I want to share my secret with you. Why? "You have our support Gareth. W".
He told the paper: 'Quite often I look at that photo of Diana at the clinic next to those frail-looking men and then I look at a photo of myself out on my bike and it motivates me because I can see how things have changed and advanced'.
"I hope that by speaking publicly about this Gareth will transform attitudes towards HIV that are all too often stuck in the 1980s".
The 45-year-old Welshman became the first United Kingdom sportsman to disclose he has the virus during an interview with the UK's Sunday Mirror - before revealing in a video on his Twitter page that he had been "forced" to make the admission.
He said he had "chosen to fight to educate and break the stigma" around the disease.
"I was being blackmailed and in my mind I thought you only get blackmailed for something really bad, which compounded the feeling of shame".
Gareth continued: "Now you have that information, that makes me extremely vulnerable, but it does not make me weak".
In his video posted on his Twitter page on Saturday, Thomas said: "I am living with HIV".
Thomas broke down in tears hugging his husband while running the Ironman race just hours after revealing he is HIV positive. He will appear on ITV as a pundit.
'I felt like an express train was hitting me at 300mph. I wasn't expecting it at all.
Gareth had to reveal his diagnosis to a string of former sexual partners so they could be tested.
HIV stands for Human Immunodeficiency Virus - the immunodeficiency is the weakening of the immune system by the virus. I have to be at the end of it a completely different person to the person I am now.
"Health Secretary Matt Hancock also retweeted the video, adding: "'I choose to fight to educate and break the stigma'.
Ex-rugby star forced to reveal HIV status to public because of tabloid newspaper..
He added: "I've been threatened by people who said they would give away my secret".
Life expectancy of people with the virus is approaching that of a person who tests negative, as long as they adhere to a combination of ongoing medications called anti-retroviral therapy.
Thomas now takes one tablet containing four medications a day and his condition is "undetectable" - meaning it can not be passed on. "I'm not just all right, I'm better than all right".
The former Cardiff Blues player won 103 caps and scored 41 tries for Wales between 1995 and 2007, and he is 13th on the all-time global test try-scoring list.