There was always a poignancy to the song Last Christmas, but George Michael could have never imagined just how poignant it was to become. On Christmas Day, it will be a year since Michael died; 25 December 2016 was not only his last Christmas – it was his last day on Earth.

There is no song that sums up the contradictions of Michael so beautifully as Last Christmas. It is cheap, schmaltzy and reeks of artifice (think of the dodgy electronic drum and plonky synth). Yet it is also a melancholy masterpiece (that anguished voice soaring in the final “I gave you my heart”). It may be based on a lie (Michael is distraught because he has been dumped by the woman he loves – Last Christmas was released in 1984, 14 years before he came out as gay) but it could not be more emotionally honest.

The video shows a group of young friends holidaying at Christmas in an Alpine ski resort. It is classic 80s (big hair, big cars, loadsamoney) with a simple, old-fashioned narrative (love, heartbreak, humiliation, yearning).

We see how last Christmas Michael’s character not only gave his girlfriend his heart, he also gave her a gorgeous brooch. And now she has dumped him for a man played by Wham! partner Andrew Ridgeley. To add insult to injury, Ridgeley is now wearing the brooch.

Michael may be beautiful, with a fringe and 4x4 to die for, but he still feels like a loser in the game of love. There is even a hint at the secret he’s keeping (“A man under cover but you tore me apart”).

Last year was Year Zero for music. Bowie, Prince, Leonard Cohen … so many music legends passed away. But it was the death of Michael, right at the end of 2016, that hit many of us hardest.

It was not only the timing (the embers of Christmas Day) or the shock (he hadn’t been ill), it was the sadness of so much promise unfulfilled. Despite his phenomenal success, for the best part of two decades he had struggled with writer’s block, addiction and depression. All the time, he promised us he was on the brink of a creative comeback. Astonishingly, despite the failure to produce new songs, his reputation did not diminish.

In a way he became his art – the reclusiveness, the recklessness, the compulsion to truth when he did emerge from the shadows. In the end, he was remembered almost as much for his lifestyle as for his music.

It may have taken him till his mid-30s to come out, but when he did … boy, did he do it in style, with the single Outside, a fabulous hymn to his conviction for cottaging in a public toilet. After that there was no holding back. He would talk at length about the joy of casual sex with strangers on Hampstead Heath, the 25 spliffs a day he got through, his arrest for possession of crack – you name it.

When he died, we waited for the inevitable sordid exposés. But they never materialised. Perhaps there was nothing salacious left to reveal about Michael.

In fact, a very different secret life of George Michael emerged, one that seemed all of a piece with the earnest sincerity of Last Christmas. This was Michael the discreet do-gooder, performing numerous anonymous acts of kindness.

I’d had first-hand experience of this generosity. The last time I interviewed him, just before Christmas 2009, Michael insisted on giving me a lift home (this was shortly before he drove into Snappy Snaps). He was not only generous, he was great fun in his generosity. He agreed to knock on the door while I hid (my older daughter answered with, “Fucking hell, it’s George Michael!”, while the younger one shouted from the top of the stairs, “Who’s George Michael?”).

Things quickly went from slightly surreal to the full Salvador Dalí when he came inside to watch EastEnders, which featured a storyline about George Michael obsessive Heather Trott giving birth to a baby she named George Michael.

After he died, the tabloids hardly bothered with the sex and drugs. Instead they shocked us with scoop after scoop about his decency – how he worked at a homeless shelter, how he paid £1.67m for John Lennon’s piano and donated it to the Beatles Story museum so it could stay in Liverpool, how he gave a woman who he had seen on Deal Or No Deal £9,000 for IVF. And on and on it went.

At a truly horrible time in our history – Brexit, Trump and the rise of populist bigotry – sad, sleazy George Michael stood out as a beacon of hope. We may have lost Michael last Christmas, but in 2017 he became a symbol of human goodness – a man who took pleasure in improving people’s lives without telling a soul.

• Simon Hattenstone is a Guardian features writer