Sport on TV: Thomas is still fighting fit in confession worth watching

To be brutally honest, it's been a good week for confessions. Lance Armstrong is in the unusual position of having committed crimes against a sport – and therefore his fellow cyclists and an adoring public – rather than in his private life. His motives for coming clean, so to speak, almost certainly involve money. He's feeling it in the pocket rather than the conscience. The non-pedalling world can only look on with bemused cynicism as he tries to recycle his reputation.

Gareth Thomas, meanwhile, did not achieve greatness on the rugby field by fooling the world that he was straight, and his team-mates and fans did not feel short-changed by his admission that he was gay. It was not performance-enhancing. Supporters would still pay the price of admission to see their hero.

My Secret Past (Channel 5, Thursday) reveals his guilt to be much more personal, caused by his inability to "come out" until he was 35. "I caused misery to those closest to me," he admits. There is no crime, only sadness. "I will die regretting the things I have done in my life," he says while staring over the cliff that he once visited every day in contemplation of suicide.

After five years of marriage he owned up to his wife, Gemma, and she left. He was at breaking point, which finally came through sport, after a game for Wales. "Rugby was a great way of hiding it all," he says, but it also gave him a forum to vent his frustrations at the concealment. "I used to relish the chance to harm somebody in a legal way. At times I felt uncontrollable."

It was after a particularly poor performance against Australia that he broke down in the corner of the dressing room. His coach approached two senior players, Martyn Williams and Stephen Jones, on his behalf and finally the secret was out, at least for his team.

But the story does not end there, and the sadness continued. Unbeknownst to Thomas, his niece was being bullied at school every day as rumours spread through the Principality. He only found this out just before the making of the programme. He also visits Ollie, a schoolboy who was being vilified by his fellow pupils for being gay.

They return to his alma mater to conduct a workshop in which the children were encouraged to confront their prejudices about homosexuality. In fact, kids seem a lot more enlightened these days, or at least more aware of what they are doing, and it is surely true that society has moved on. But the fact that racism is still rearing its ugly head in football is a clear warning that we should remain vigilant.

As a rugby player Thomas was a role model, and his efforts to help others are a concerted effort to fulfil that obligation, albeit in a different way. But if society is improving, homophobia is still rampant in what Martyn Williams calls "manly, macho sport" – and in football. Especially football.

The fight against prejudice would be hugely enhanced if sporting heroes could be out and proud. But it took Thomas a long time to get to that point. Perhaps this programme might help the weird world of sport to catch up with the rest of society.

Thomas is also appearing on the new Dancing on Ice (ITV1), having already demeaned himself on Celebrity Big Brother a year ago. Any more reality TV paydays like this and he may start getting some entirely justified abuse.