Gareth Thomas has revealed that he is HIV-positive.

The former Wales rugby star, who came out publicly as gay in 2009 and retired from the sport in 2011, made the announcement Saturday in a video shared on Twitter.

"I want to share my secret with you," Thomas says in the video message. "Why? Because it’s mine to tell you. Not the evils that make my life hell by threatening to tell you before I do. And because I believe in you and I trust you."

"I’m living with HIV," the 45-year-old athlete continues. "Now you have that information, that makes me extremely vulnerable, but it does not make me weak. Now, even though I’ve been forced to tell you this, I choose to fight to educate and break the stigma around this subject. And that begins today."

"Everyone lives in fear of people’s reactions and opinions to something about them," Thomas concludes, "but that doesn’t mean we should have to hide."

"I’ve been living with this secret for years," Thomas tells the Sunday Mirror. "I’ve felt shame and keeping such a big secret has taken its toll. I had a fear people would judge me and treat me like a leper because of a lack of knowledge. I was in a dark place, feeling suicidal. I thought about driving off a cliff."

"I was being blackmailed and in my mind I thought you only get blackmailed for something really bad, which compounded the feeling of shame," he adds, not naming the tabloid newspaper that had learned of his HIV diagnosis.

Thomas credits a "strong support system" for helping him survive this emotional period, including his husband, Stephen, whom he met after discovering he was HIV-positive.

"Many people live in fear and shame of having HIV, but I refuse to be one of them now," Thomas says. "We need to break the stigma once and for all. I’m speaking out because I want to help others and make a difference."

The Proud author also reveals he found out he was HIV-positive during a routine sexual health test. "I immediately thought I was going to die," he recalls. “I’d never known anyone with HIV or AIDS. And everything I’d heard about HIV was death and frailness."

Thomas, who now receives regular counseling, says he takes antiretroviral medication and that the virus is undetectable.

An ITV pundit for the Rugby World Cup, Thomas is competing today in the Wales Ironman event. "I’m fitter now than when I played rugby and I didn’t have HIV then," he says. "I’m not just all right, I’m better than all right."

Gareth is also the subject of a new BBC documentary, Gareth Thomas: HIV and Me.

Last year Thomas was beaten in a homophobic attack. He decided not to press charges, instead asking his assailant for an apology.