God knows what I must have looked like: a bedraggled 25-year-old dressed as a psychedelic game hunter with glitter smeared across my face crying hysterically in a Cambridgeshire field. It was 4pm on 23 July 2011, and a friend of mine had broken the news to me: Amy was dead. I was totally inconsolable, while around me fellow-revellers danced.

It was the Saturday of Secret Garden Party and my friends had been deliberating among themselves how best to tell me. Their hands were forced when they realised it was about to be announced on the festival stage. In the end, a guy called Jamie opted for directness: “Amy Winehouse is dead.”

These words reverberated through my brain and body. All I could muster were the words, “No, no, no,” as I doubled over. I still get a lump in my throat when I think about it, and feel a desperate need to pick that girl up off the dirty ground to give her the care she needed. Rather than console me, most of the group decided to leave me, because I was “bringing the vibe down”. The rest is a bit of a blur.

For many who heard the news that day, Amy’s death marked the end of an era. For me it was also the beginning of a new, painful chapter: the start of a grieving process that would consume me for a decade. I don’t know what it is to lose someone who isn’t in the public eye, who isn’t famous. It may not be easier. I’d hope, at least, to be afforded space and privacy; room to heal and time to process – all things I desperately longed for in the years to come.

I first met Amy in 2005. My friend Jon and I were on a night out at Soho’s Freedom Bar. We spotted this handsome guy sitting with a striking girl across from us. Amy’s debut album, Frank, had been released, but I wasn’t aware of who she was; her music wasn’t on my radar. It was only after someone said her name that I registered her familiar face.

Half an hour of plotting and planning followed, after which Jon sent two martinis to their table. Right away, the pair bounded over with huge, playful grins. Apparently, they thought we were giving them “evils” and were about to come over to kick off.

A bond formed that night. I don’t know how or why, but right away Amy and I found comfort in each other. In time we’d recognise ourselves to be two of life’s misfits and our friendship cemented in the years that followed.

Amy asked me to work for her in late 2006, making her my first big client since I’d started out as a stylist. Back to Black had just been released and it was picking up momentum, but Amy’s world was still pretty normal. When we went to her house, Amy would cook dinner; we’d drink wine and chat for hours. Other times we’d go out for a night in Camden: the Hawley Arms, the Good Mixer and Marathon Bar, before ending up at Koko if it was a Friday night. I look back on those heady days with such fondness – a stark contrast to what followed.

Things started to change at the Brits in 2007. Overnight, Amy became a household name and suddenly paparazzi were everywhere. By 2008, she’d covered magazines and walked every red carpet. Amy had got married, developed a serious drug habit, seen her husband jailed and moved house; she acquired 11 kittens and photographers camped day and night at her door.

Alongside this, at 21, I was also grappling with my own problems. Amy had introduced me to a man and we had started dating. It was an abusive relationship and Amy – despite being in her own pit of hell – rescued me, moving me into her other address. For that I’ll be forever grateful.

When Amy died, I didn’t have a moment of peace to process what had happened. Her death wasn’t just our loss, it was a global “story”. Her face was on every front page; a sea of condolences poured in. Most were reassuring, but some I found odd and intrusive.

Everyone seemed to think they knew what had happened and why – they had so many opinions. Obsessed with the story, people asked deeply personal, inappropriate questions about Amy’s death, while others hoped to enlighten me. Did I know what they’d read in the news? Nobody could separate the celebrity from the person I knew and loved.

Even her funeral was a spectacle. Hordes of paparazzi were standing at the gates to the crematorium. A journalist found his way into the ceremony; someone burst through the back door and lay on the coffin, sobbing like a scene from a bad movie.

Back in the UK, people had become bolder with their remarks: “Why didn’t someone do something?” We did. “I would have done it like this.” Yes, we tried that. “Someone should have dragged her to rehab.” Yep, did that, too. Several times. We tried everything, but these comments plagued my thoughts. Sometimes they still do.

I can empathise. Amy’s problems were presented in a simplistic vacuum. Lots of people loved her. Only a few of us knew the truth, so the public – fans and all – relied on the often unreliable press. Personal, private moments weren’t shared; her inner circle did not talk to the media. I don’t blame people for being confused and concerned. But for me, that didn’t make it easier to cope.

And then, finally, some time in 2014 – three years after we lost Amy – at last things seemed to go quiet. Her music was still being played in shops and on the radio, but with less frequency; nobody new seemed to be crawling out of the woodwork to talk about her life. The silence sparked a visceral and delayed reaction. What had happened finally hit me – and I went off the rails.

I neglected my mental health, drank heavily and made bad decisions – started toxic friendships and another unhappy relationship. I was drowning in the trauma of Amy’s death and the way it played out in public. I desperately tried to keep my head above water. If it hadn’t been for a couple of friends and my family, who orchestrated rescue missions on many occasions, I’m not sure I’d have survived.

Another harsh truth, which I was only just confronting, was that I had lost not only my friend but my career. Amy had been the focus of my professional life; my “job” had effectively vanished. The fallout from her death had broken me so deeply that I was utterly incapable of resurrecting what – for years – I’d worked to build.

I was broke and living with my mum – grief-stricken, gaunt and traumatised. I desperately needed to start processing what had happened, but couldn’t even speak to professionals. I’d had a therapist who, mid-session, started telling me about what she’d have done for Amy and how she’d planned to reach out to her. Could I put her in touch with Amy’s dad?

Instead, I shifted my focus. Maybe, I thought, I’ll be able to find peace when Amy’s story is at peace as well. For years, Amy’s light and life had been turned into a grubby tabloid myth. Her truth had been lost, and I needed to find it again. For me, that meant changing the way she was remembered in both life and death.

I made it my mission to create something to celebrate her: she was inspiring, strong and loving. I wanted the world to know the Amy I knew, not the version from the headlines. The one who cooked for me, played pool with me and made me laugh. The one who saved me even though I couldn’t save her.

I began working on a book, an exhibition and a short film celebrating her achievements. The more I focused on all this positivity, the better I felt.

Over time, the anger and confusion has subsided. I started to rebuild my career and moved back to London. The tabloids found new people to focus on and as a society, I think, we became more understanding about substance abuse and mental health issues.

Losing someone famous had for years felt like a never-ending struggle, but today I see some positives. I can listen to Amy’s music again with a newfound appreciation, taking comfort in hearing her voice. I can spend time in her presence by watching interviews with her online. I’m not sure I’ll ever get over what happened, both Amy’s death and how it happened so publicly. But at least I know she’ll never be forgotten. Amy was loved, very loved, and she always will be.

Amy Winehouse: Beyond Black, curated by Naomi Parry, is published on 14 September (Thames & Hudson, £30). Buy it for £26.10 from guardianbookshop.com