Watching the documentary, Amy, about the short but stellar life of singer Amy Winehouse, you get the sense of a Jewish tragedy unfolding before your eyes.

As with the most potent of tragedies - from the Greeks, through Shakespeare and Racine, Ibsen, to Tennessee Williams and Arthur Miller - the momentum, the fate, is ineluctable. The heroine, succumbing to her flaws, heads towards her end and there's nothing anyone can do about it.

I wanted to reach into the screen and stop it all. But what could you or I have done? Give out hugs, advice, warnings, counsel? We are powerless, yet also, in our role as voyeur, made complicit in the tragedy.

"The more you see it go along, the sadder it gets," agrees the film's director Asif Kapadia. "Certainly, the more I found out as I made it, the sadder it became. I remember I had an urge to stop it back when it was happening - how can someone die like this, in this day and age, right in front of our eyes? To the extent that we could all see which path she was headed down. As director of that story now, I suppose I could have altered it, but you can't hide what happened, and can only hope that, maybe next time we see it, we'll recognise it and people can do something about it."

Since the film's debut at Cannes in May, it has been the subject of much acclaim but no little controversy. No truly Jewish film should be without its broiges and the topic of Amy Winehouse, who died almost exactly four years ago, in July 2011, at the age of 27, seems to have touched everyone, not just her still-grief-stricken family and friends.

They all loved Amy but couldn't come together to help her in the end

Comment: Amy and me — the story of how I rejected her

"I knew going into this that it was sensitive and that I would have to be sensitive," says the Hackney-born Kapadia, who grew up in Stamford Hill and then lived in Kentish Town. "This was a London story about someone who lived around the corner, someone I might have known. That was my way in. I was a London boy and she was a London girl."

I have known Asif for many years. I know his wife and family and he's a film-maker with a great heart, a nice Indian boy making a film about a nice Jewish girl. Did his own ethnic background help him as he was, slowly, allowed into the community and the intimate circle of Jewish friends and family, with whom Amy identified?

"I think it was my skills as a person that helped," he says. "I could make them feel comfortable, allow them to trust me. I'm not from the music industry, I had no connections, no agenda. Maybe it helped I wasn't from the same community, but a similar one. I don't know. I was an ear most of the time, just listening as they let out a lot of pain."

What's extraordinary about Amy the documentary is that, for all the 100-plus interviews Kapadia conducted in researching the film and the 2,000 hours of footage assembled, he doesn't use the traditional "talking head" format. Instead, voices float in and out and it creates a sort of biopic but using real-life footage and archive.

Of course, the director has shaped this "truth" into his own perception of it, to tell the story how he, after intense months of scrutiny, sees it and, of course, this vision might not chime with everyone's. Already, Amy's father Mitch has very publicly taken issue with the film, which, admittedly, doesn't cast him in the best of lights.

"Look," counters Asif. "The people I talked to had been carrying these feelings with them a very long time, mostly privately, never expressing them to anyone. These interviews got dark, heavy and deep. There were tears. They all felt they were alone, but suddenly I could see many different people feeling connected to Amy all around the world, not knowing each other at all, all feeling the same way. And that was, clearly, that they loved Amy but somehow they didn't all come together to help her, to make things happen for her."

From the film, one certainly gets the impression there's a blame game going on. I'm not sure there are answers, although there are plenty of questions, and audiences will form their own opinions and cast their own villains. But was there anger, guilt and frustration mixed in, too?

"The predominant feeling was actually that they all blamed everyone else for enabling her. They all thought everyone else was bad for her. It was amazing to me how they had so much in common in their love for Amy and they were all good people - but, you know, Amy also kept everyone in compartments, her own little private relationships all over the place. So I suddenly become the person joining the dots to create the fuller picture."

The film is probably even more heartbreaking than you imagine . Part of that power comes from it not only being a biographical re-appraisal as Asif mentions above, but also a musical re-appreciation.

You realise, in merely a couple of albums - Frank and Back to Black - just how good this talent was, a north-London, world-class, jazz diva the like of which the Anglo-Jewish community has never had before.

I'm not sure we cherished her enough collectively at the time. She was a proud Jew, wearing a Magen David around the world. Yet did we turn, if not our backs, but our noses up when she went off the rails with the drink and drugs? Who honestly didn't think somewhere in the back of their mind: if she'd just go with a nice Jewish boy, this mishegas wouldn't have happened? Kapadia felt it. "I often wondered, if she was more religious, would that have helped and given her something to cling to? But even then, her music had so much soul and spirituality in it and that couldn't save her."

For Asif, part of the sadness was learning that Amy did have plenty of warmth and family around her. "She used to go to her grandma's and she learned a lot from her example, not just a love for old-time jazz and band music. Amy herself was a matriarch. She liked to cook, she looked after everyone, fed them, worried about others more than herself. Later, from what I learned, she really did dream of settling down, having kids. Yes, I think she wanted to be a Jewish mother."

And yet, as we all know, she said No, No, No. Amy was, instinctively, a rebel and her actions suggest she wanted to get out of the suburban cosiness of Southgate and East Finchley, seeking out the edgier waters of Camden.

It was then that she became a fixture on the London streets and in the papers. As the film's editor Chris King recalled to me last week at a special UK Jewish Film preview of Amy: "You'd be out in Camden or in Soho and in the distance, down the street, you would vaguely hear and see the glow of flashbulbs, you'd feel a jolt of noise and energy, and that was her, that was Amy, surrounded wherever she went."

The film conveys the paparazzi's hounding, as well as Amy's own sense of drama in front of the cameras. Most seem reluctant to blame Amy herself for any of this.

So perhaps the real stroke of genius, the real revelation, in the documentary is the use of Amy's handwritten lyrics, which look like the jottings of a little girl, with heart-shapes dotting the i's, but which contain wit, poetry and startling emotional wisdom.

"These are lyrics which suggest a maelstrom, that she was drawn to pain and struggle, that these were somehow attractive," suggests Asif. "It reads to me that her insecurities were also her motivation."

Tony Bennett, with whom Amy duetted, believes she was up there with the jazz greats such as Billie Holliday and Dinah Washington. But he also gets the last word in the film, intoning that you learn how to live life if you live long enough. "Maybe Amy just didn't get through the tough time to find out what she would do next."

And that is her tragedy. For us, it's certainly a great loss and we can only guess at what more she would have given us in terms of great songs as well as great performances of them.

It would be an awful misinterpretation to focus on the pain, because there is great inspiration here, too, using Amy's own words, own lyrics, Amy's self and, of course, her voice.

Was there a moment when Asif ever wished he could be making a fiction film and, in which case, who could have played Amy?

"Yeah, and who could drive like Senna," he adds, referring to his BAFTA-winning documentary about the Brazilian motor-racing driver.

"You know, I don't want anyone pretending to be Mohammed Ali. For me, a lot of this film is just spent looking at the real Amy - we see her face change from that of a teenage girl, her shape changes, her eyes change. But when actors do it, it feels self-conscious: look, I've lost weight, look I've gained weight, or oh I've got muscles here and look how I get this walk right. And even if an actor can sing, they can't sing like Amy, or it would be doing an impression, so the real thing is more emotionally engaging to me.

"The real test of both Senna and Amy would be that nobody could make a better version as fiction, although rumours persist about both. Real life is more complicated and layered than movies, and you can get that across in a doc. With a fiction movie, the script is always questioned by people along the way - can we simplify, can we make it a happier ending?

"A documentary doesn't have to answer those questions. There isn't a happy ending in Amy, but I still hope I've shown how good she was."

Amy is on general release.