For years, I associated female friendship with alcohol. Although Kate and I had been friends since we were five and didn’t start drinking until a decade later, in many ways my relationship with her was inextricably linked to my relationship with booze.

We met at primary school and instantly became inseparable in the way that little girls do, in a romantic, monogamous way that I still find curious: eternal, undying love for one person. As my parents’ marriage collapsed, my friendship with Kate deepened.

Her family swept me up, something I gladly accepted, grateful for what I considered to be a normal family. When my mother came to collect me, I’d dig my fingers into the palm of my hand and refuse to come downstairs.

‘You’re hurting yourself!’ Kate would shriek. ‘Don’t do that, it’s scary.’

In a strangely premonitory way, this was the first of many such conversations. Over time, we would both hurt each other.

Aged 11, we ended up going to different London schools but swore we would never find another best friend – and I think we meant it. We still spoke for hours on the telephone in the evenings and went riding together at the weekends.

But cracks were beginning to show: she was less available than she used to be. ‘I’ll get her to call you back,’ her mother would say all too often.

But if there’s one thing that will temporarily cement a relationship, it’s alcohol, and we soon discovered its restorative charms.

Hetty and Kate became best friends in primary school and started drinking when they were 15 (picture posed by models)

Aged 15, I invited her over when my mother was out, an increasingly frequent occurrence as she was about to remarry.

As teenagers, Kate and I frequently drank to excess. This was the late Nineties and early Noughties, a time when heavy drinking and feminism joined hands in the ‘have it all’ culture.

Getting smashed with other women was sold to us as evidence of hard-won equality. We too could have the heavy boozing friendships that were once the preserve of the men.

As best friends Sadie Frost and Kate Moss fell out of bars together and Sex And The City’s Carrie Bradshaw turned up hungover to work, so did we.

‘Bridget would,’ we used to laugh as we stole another bottle of my mother’s wine and lit our 20th Marlboro Light of the evening in homage to our boozy heroine Bridget Jones.

We drank a lot for two teenagers – certainly well over the average: two bottles of wine between us whenever we met and more besides if we started drinking at lunchtime, which we often did.

We continued to drink our way through university, early jobs, dodgy living arrangements and even dodgier boyfriends.

Did I drink more than her? Not really, but the consequences on my life were far more profound.

Getting smashed with other women was sold to us as evidence of hard-won equality, writes Hetty Moorehead (picture posed by models)

I guess you could say we drank for different reasons: she for the light and the fun and me for the dark release of my demons.

I have thought long and hard about what alcohol does to female friendship and I still can’t quite explain its strange alchemy.

Picture the scene: a snug in a pub or the clean minimalism of a wine bar where you settle down with a bottle of wine to catch up.

Quickly, alcohol accelerates the speed at which you give yourself away and tell your darkest secrets. Alcohol makes you believe that your female companion is your emotional double.

Conversation is spattered with, ‘Oh my God, yes, me too, that’s exactly how I feel’. We expect a deep and profound reciprocity from our female friends and alcohol undoubtedly eases the flow.

Yet this deeply confessional stream is as toxic as it is intoxicating. The fact is, alcohol creates a trick mirror. You can never see yourself in another person; believe me, I’ve tried.

I didn’t know it at the time, but I had gone way past the Bridget Jones mark.

In hindsight, by my late teens I was already in the grip of an illness whose name I found repellent: alcoholism.

While other female friends would get up and go to work or lectures after a night of girls-together boozing, I could hardly move, lost in a depression that threatened to engulf me, my hands shaking so much I could hardly leave the house. I lost jobs, I lost all self-respect, and, eventually, I lost many female friends.

Aged 25, I knew that something was wrong, but I was too in love with alcohol to point the finger at it. Hadn’t alcohol given me my friends and my sense of identity? I couldn’t countenance saying goodbye. Now a new narrative began – one that would change my life for ever.

Kate, my ride or die, became exasperated with me. ‘I think you just need a night off,’ she’d say as I told her about my depression. ‘You don’t have a drink problem.’

I framed my alcoholism as part of a depressive illness, but she thought I was exaggerating and told me to pull my socks up.

We were back in the old dynamic of victim and white knight forged as children when her parents had helped me. But I couldn’t keep drinking just for her, could I?

On the day I went to my first AA meeting, I didn’t dare tell Kate where I was.

A week earlier she had driven 50 miles to rescue me from a hangover, joking that what I really needed was a glass of wine and a lie-down. I smiled, but something in me had shifted.

As I broke away from booze, I broke away from her, too. That’s the sorry truth of it. Scared of her reaction, I dreaded telling her I had given up. On the day I announced the news to her, as we sat in a cafe, I felt as if I was asking her for a divorce.

‘Can’t you just drink sometimes?’ she asked.

I didn’t have the heart to tell her it was meant to be for good. Or maybe I hadn’t woken up to that fact myself.

Throughout my first year of sobriety, as I stood sober at weddings and parties, she crowed to assembled groups ‘that I used to be such fun’. I laughed but inside felt the pain of loss, of my old self and her friendship.

When I had a year sober, friends took me out to brunch; she wasn’t one of them.

At my wedding, I watched her drinking champagne across a crowded room and felt as if she couldn’t be further away from me if she tried. I can’t put my finger on a single instance when the friendship came undone. But as I began a new life in recovery, our poles simply moved apart.

I made sure not to arrange things with her on a Sunday when she might be hungover and I’m sure she stopped telling me things that had happened on nights out.

We went from being in each other’s pockets to the occasional midweek dinner and then, imperceptibly, to nothing at all.

Over the 15 years I have now been sober, I have had to accept that some friendships – particularly the formative ones built on the foundations of alcohol – can’t withstand the emotional earthquake of sobriety.

To many of those you used to drink with, getting sober is an act of betrayal or an implicit criticism of their habits. Nobody likes to feel the spotlight of sanctimony upon them, and I truly can understand that.

Happily, not everyone sees it this way.

The old girlfriends I have kept from childhood tell me they can’t remember the person I was when I drank.

The new friends I have made from motherhood tell me it never occurred to them to ask why I don’t drink.

I used to think about Kate a lot, imagining scenarios where our lives might come together again. But I’m not sure she would even recognise me now. Fifteen years is a long time and I am a different person.

We all are.

Hetty Moorehead is a pseudonym, all names and identifying details have been changed