It was a Saturday night in early October 1986. My 30th birthday party, or what passed for it. Just a handful of junkies and my few remaining friends sitting on the floor of a grey, bare room in a flat in south London. I had thought it would be fun, as, for once, there was no shortage of heroin. Instead, I felt wretched.

I was in total despair, as a rare moment of self-awareness had kicked in. It wasn’t just that I had trashed my entire 20s, achieving almost nothing of any note; it was also that I could see no prospect of any future. My self-destruction was complete. I had hit rock bottom. It was a terrifying moment, so there was only one thing for it. Take more and more drugs until I fell unconscious. Happy birthday to me.

For most drug users, heroin is the ultimate taboo. For me, not so much. I embraced it, actively sought it out. When I first took it, at 20, it was like connecting with an old friend. I felt warm, invulnerable. It was the barrier between me and the outside world that I had always been looking for. All my feelings of low self-worth, failure and self‑loathing swept aside. I didn’t need anyone or anything else.

Not that I intended to become an addict. Like every other junkie I have met, I thought I could beat the system. I would be the one able to control my intake; the smack wouldn’t control me, thank you very much.

For the first few years, I just about got away with it. I set myself strict limits, like taking heroin only on Saturdays. But everything became blurred. Saturdays rolled into Sundays. No real harm done. Then I didn’t see why I shouldn’t start on Fridays. Then Mondays. To take the edge off the weekend. Before long, I was taking it every day. Then, one morning, after a day in which I couldn’t get any drugs, I woke up to find I was sweating, had severe cramps and needed to throw up. It took a while for it to dawn on me that I had a habit.

The next eight years were ones of not-so-steady decline, years in which I did all the things I had always sworn I would never do. Injecting heroin was only for real addicts, so I would never do that. Except I did. All the squalor, rip-offs and shabby betrayals associated with drug addiction became part of my everyday life. Lying and cheating became second nature. I did get a number of shitty jobs, but could never hold them down, as being a junkie was a full-time business. I lost count of the hours I spent hanging around in cars, pubs and street corners, waiting for dealers to turn up. There were no mobile phones; back then, you had to work for your habit.

I tried to give up on countless occasions, either by slowly reducing my daily intake or going on a methadone cure, but nothing worked. I didn’t know any addict who had managed to get clean. But with every failure, my self-esteem fell lower and my sense of futility grew. Above all was the sense of shame at what I had become. It is always the shame that gets you in the end. Almost everyone had given up on me. I had given up on me.

My rock bottom lasted for the best part of six months. The feelings of despair that had overwhelmed me on my 30th birthday grew steadily worse. I wanted to give up, but had no idea how to do it. So, increasingly, I sought self-annihilation. My using became worse and worse. I would shoot up, only to come round lying on the floor much later. Overdosing became a way of life – the only way I could medicate my self-hatred.

Then came a moment of clarity. Or a miracle. Call it what you will. I was challenged to stop by my wife – whom I had married in 1985 and who had stuck by me despite everything – and one of my last friends. And rather than just fob them off by saying I would do yet another methadone cure that I knew wouldn’t work, I agreed to do whatever they suggested. My desire to live was, briefly, stronger than my desire to die. A few days later, they came back with the name of a rehab centre. I had barely heard of such a thing, let alone known someone who had been to one. Within a week, I had been admitted.

I can’t remember much of my four-week stay in rehab, other than they made me go cold turkey – I was sick as a dog and barely slept for the first two weeks – and that I was astonished to hear that I would have to stop taking all drugs, including alcohol. There must also have been therapy groups, but by far the most important thing rehab gave me was an introduction to the 12-step programme.

I will never forget my first Narcotics Anonymous (UKNA) meeting. I sat at the back, shaking with fear and entirely mute. What I heard changed my life. Here were addicts with months and years of clean time – something that seemed an impossibility – whose stories were similar to mine and who were talking about feelings with which I could identify. I had never known such people existed or that recovery was possible. It was like a homecoming.

Meetings became a lifeline for me when I came out of rehab and I felt ridiculously proud when I was chosen to be the greeter, offering tea and coffee. Then again, I was the only person to volunteer. The meeting secretary later told me his heart had sunk when I had put up my hand, because he was certain I would last only a few weeks before relapsing and disappearing without trace.

But I kept coming back, made lasting friendships and slowly rebuilt something that approximated to a normal life. Finding work proved problematic: who would want someone with an unexplained 10-year gap in their CV? Yet after a couple of years of part-time jobs, I was inspired by a friend I admired in UKNA to write. I sent something off to the Independent on Sunday and they accepted it. Mainly, I think, because they thought I was the novelist Jim Crace. No matter; I had an in. Soon I was writing regularly for the nationals and had been offered a book deal to write about cricket.

It took time for relationships to mend, for former friends and members of my family to trust that my recovery wasn’t yet another flash in the pan. But slowly, after a lot of therapy – I am still with the same therapist 30 years on – things took shape. After five years, my wife and I even felt secure enough to start a family, that we had the resources to be decent parents. Our children are now 29 and 26 and are far more emotionally articulate and accomplished than I was after many years of giving up drugs. I could not be more proud of them.

Even so, recovery has not been easy. Many of my friends and acquaintances have died. Aids, hepatitis C, suicide and overdosing after a relapse accounted for many. Incidences of cancer and heart disease also seem far higher in recovering addicts than in friends who didn’t spend years abusing their bodies. No one gets away scot-free.

My mental health is a tussle with depression and anxiety and I am often on the losing side. There have been many days when I can barely get out of bed because I am having a panic attack, while nightmares are an almost nightly occurrence. I regularly have dreams in which I am back taking drugs. Twice, things have got so bad that I have had to be admitted to a psychiatric hospital – most recently this summer. Even on the good days, low self-worth and a lack of self-confidence are ever present. The desire to disconnect, to disappear, can be overwhelming.

I am in little doubt that if I had continued taking the quantities I had been using in the last year of my active addiction, I would have been dead within six months. Just another junkie statistic. Mourned by a few and long since forgotten by everyone else. Yet here I am, nearly 35 years later, still buggering on, my life far fuller, richer and longer than I could ever have dared imagine at my rock bottom. I couldn’t have done it without the love and support of so many people. To all of them I owe a debt of gratitude I can never repay.

A Farewell to Calm by John Crace (Guardian Faber, £9.99) is out now. To support the Guardian and the Observer, order your copy at guardianbookshop.com. Delivery charges may apply

In the UK and Ireland, Samaritans can be contacted on 116 123 or by emailing jo@samaritans.org or jo@samaritans.ie. The mental health charity Mind can be contacted on 0300 123 3393 or by visiting mind.org.uk. In the US, the National Suicide Prevention Lifeline is 1-800-273-8255. In Australia, the crisis support service Lifeline is 13 11 14. Other international helplines can be found at befrienders.org