I was in the cinema for about 15 minutes before I started crying. Not crying as in the occasional tear quietly trickling down my cheek: really sobbing, in that loud, unguarded, emotionally destroyed way that makes people turn around and look at you with alarmed expressions. I was watching my family – my mum and dad, my nan – in my nan’s old council house in Pinner Hill Road in the late 1950s, singing I Want Love, a song Bernie Taupin and I had written in 2001. I knew it was in the film, but I didn’t know how they were going to use it. Up until that point, I’d kept a discrete distance from the actual process of making a movie about my life. I gave some suggestions, saw a few daily rushes, said yay or nay to some important decisions and met two or three times with Taron Egerton, who plays me. But otherwise I’d kept well away from Rocketman, letting my husband David [Furnish] be my eyes and ears on set every day. I figured it would be uncomfortable for everyone to have the person the film was about lurking around.

So I wasn’t prepared for the power of what I was seeing. I Want Love is a song Bernie wrote, I think, about himself: a middle-aged man with a few divorces, wondering if he’s ever going to fall in love again. But it fitted life in Pinner Hill Road perfectly. I suppose my mum and dad must have been in love once, but there wasn’t much sign they ever had been by the time I came along. They gave every impression of hating each other. My dad was strict and remote and had a terrible temper; my mum was argumentative and prone to dark moods. When they were together, all I can remember are icy silences or screaming rows. The rows were usually about me, how I was being brought up.

Hot seat: Taron Egerton, Elton John and David Furnish on the set of Rocketman. Photograph: David Appleby

My dad was in the RAF so he was away from home a lot, and when he got back, he tried to impose new rules about everything: how I ate, how I dressed. That would set Mum off. I got the feeling they were staying together because of me, which just made things more miserable. The best way to escape it was to shut myself in my bedroom with my record collection and my comics, and drift off into an imaginary world, fantasising that I was Little Richard or Ray Charles or Jerry Lee Lewis. I made my peace with it all years ago. They divorced when I was 13, both remarried, which I was happy about, although my relationship with both of them was always tricky. I was closer to Mum than Dad, but there were long periods when we didn’t speak. And my childhood is one thing I’m still sensitive about.

Even if I hadn’t been, the whole experience of watching someone else pretend to be you on screen, of seeing things you remember happening again in front of your eyes, is a very weird, disconcerting one, like having an incredibly vivid dream. And the story of how I ended up in a cinema, crying my eyes out at the sight of my family 60 years ago, is a long and convoluted one. And it begins, naturally enough, with a naked transgender woman with sparks flying out of her vagina.

The trans woman was Amanda Lepore, a model, singer and performance artist. She had sparks flying out of her vagina because she was starring in one of a series of films by David LaChapelle I’d commissioned for my show in Las Vegas, The Red Piano in 2004. That was his interpretation of the lyrics of Someone Saved My Life Tonight, a song Bernie and I had written about our pre-fame years, living in a flat in north London with a woman I’d foolishly got engaged to when I was still very confused about my sexuality.

An actor was dressed as me in full 70s stage outfit sticking his head in a gas oven, homoerotic angels figure-skating with giant teddy bears and Amanda Lepore, naked, in an electric chair, with sparks flying out of her vagina. I loved it: I’d said all along I didn’t want a standard Vegas show, and no one was ever going to be able to call The Red Piano that.

‘I told Rod Stewart to turn the role down’: Elton John in rock opera movie Tommy (1975). Photograph: Michael Ochs Archives/Getty Images

But it also got me thinking. David LaChapelle’s films were based, very loosely, on my life. I really had staged a completely ridiculous suicide bid that involved sticking my head in a gas oven. Rather than tell my fiancée I’d made a mistake, that was my brilliant plan to try and get out of the wedding. If you were going to make a film about me, that would be the way to do it. Nevertheless, the idea of making a film about my life still seemed like a big IF. For one thing, I’ve been very successful writing songs and soundtracks for films, but I’ve never been very comfortable with seeing myself on a big screen.

Amazingly, the director Hal Ashby offered me the male lead in Harold and Maude in 1971, but I turned it down: I loved the script, but it seemed like the wrong thing to do at the time. I’ve played myself in a couple of films, none of them exactly Oscar winners: Spice World and a Disney thing called The Country Bears. I suppose my one famous film role was in Tommy, although it didn’t really involve acting, just trying not to fall over while wearing a pair of 4½ft Doc Martens. I initially turned that down, too. They contacted Rod Stewart and I told him to turn it down as well. “I wouldn’t touch it with a bargepole, dear.” Then Pete Townshend from the Who rang me and I felt like I couldn’t say no. Rod was absolutely furious: “You bitch! You did that on purpose!” I’ve obviously spent a significant proportion of my life deliberately trying to annoy Rod Stewart – that’s very much the nature of our friendship – but that time it was completely accidental.

‘I hadn’t even wanted to be a rock star’: Elton John on stage in 1974. Photograph: Michael Putland/Getty Images

I’ve never been very interested in looking back at my career. It happened, I’m incredibly grateful, but I’m more interested in what I’m doing next rather than what I did 40 years ago. But that began to change a little the older I got, and I really started to approach things in a different way when I had children. I was 63 when our first son, Zachary, was born, 65 when Elijah came along – and I did start thinking about them in 40 years’ time, being able to see or read my version of my life. I became less conscious about keeping it all to myself. I liked the idea of them having a film and an autobiography, where I was honest.

In some film scenes I’m disgusting and awful. But at my worst, I was

So when I decided I did want to go ahead with a film, we commissioned a script from Lee Hall, who I’d worked with on the stage musical of Billy Elliot. It was brilliant. It had moments that were pure fantasy and moments that were really hard-hitting, no punches pulled, like Tantrums and Tiaras, the documentary my husband David made about me not long after we met. Lots of people told me I was insane to allow that documentary to be released, but I loved it, because it was truthful. There are moments in it – and moments in the film – where I’m completely disgusting and awful, but then, at my worst, I was disgusting and awful, and there’s no reason to pretend otherwise.

But actually making the thing took years. Directors came and went – David LaChapelle was going to do it, but then he decided to focus on his fine art career – before the producer Matthew Vaughn, who I’d met when I had a cameo role in Kingsman: The Golden Circle, suggested Dexter Fletcher. So did lead actors: Justin Timberlake and Tom Hardy were both in the frame before Taron came along. Some studios wanted to tone down the sex and drugs so the film would get a PG-13 rating. But I just haven’t led a PG-13 rated life. I didn’t want a film packed with drugs and sex, but equally, everyone knows I had quite a lot of both during the 70s and 80s, so there didn’t seem to be much point in making a movie that implied that after every gig, I’d quietly gone back to my hotel room with only a glass of warm milk and the Gideon’s Bible for company.

Birthday bash: Elton John and David Furnish attend his 50th party at the Hammersmith Palais in London, 1997. Photograph: UK Press/Getty Images

And some studios wanted us to lose the fantasy element and make a more straightforward biopic, but that was missing the point. Like I said, I lived in my own head a lot as a kid. And when my career took off, it took off in such a way that it almost didn’t seem real to me. I wasn’t an overnight success by any means – I’d been slogging around the clubs, making records, writing songs with Bernie and trying to sell them to people who weren’t interested for four or five years before anything big happened. But when it happened, it went off like a missile: there’s a moment in Rocketman when I’m playing onstage in the Troubadour club in LA and everything in the room starts levitating, me included, and honestly, that’s what it felt like.

I left England in August 1970 more or less unknown. Me and Bernie were so broke, we were sleeping in bunk beds in my mum and stepdad’s spare room. I was making ends meet working as a session musician, playing on anyone’s records. I’d had a little bit of press and a few plays on John Peel for my second album, Elton John – enough that I didn’t see the point of going to perform in America, where literally no one knew who I was. But I came back from the States a month later with American critics calling me the saviour of rock’n’roll. Artists who were just mythic names on the back of album sleeves to me, people I absolutely worshipped, were suddenly turning up in the dressing room to tell me and Bernie they loved what we were doing: Brian Wilson of the Beach Boys, Leon Russell, the Band, Bob Dylan. I’d also lost my virginity, to a man – John Reid, who later became my manager – and come out as gay, at least to my friends and family. This all happened in the space of three weeks. To say it was a lot to take in is a terrible understatement.

‘I came back from the States with American critics calling me the saviour of rock ’n’ roll’: John with his mother Sheila and stepfather Fred Fairebrother at their apartment, London 1971. Photograph: John Olson/Getty Images

Understandably, Bernie and I had no idea what the hell was going on – you know, I hadn’t even wanted to be a rock star in the first place, I just wanted to be a successful songwriter – but it just got bigger and bigger over the next few years. I kept a diary the whole time, and it’s inadvertently hilarious. I wrote everything down in this matter-of-fact way, which ends up making it seem even more preposterous: “Woke up, watched Grandstand. Wrote Candle in the Wind. Went to London, bought Rolls-Royce. Ringo Starr came for dinner.”

I suppose I was trying to normalise what was happening, but the fact was, what was happening to me wasn’t normal. I’m not complaining at all, but there was no way you could prepare yourself for it. I don’t think any human being is psychologically built to cope with all that stuff happening to you that quickly, let alone me, with all my neuroses going back to my childhood.

It took a Herculean effort to get noticed for taking too much cocaine in 70s LA, but I was prepared to put the hours in

In a way, it’s a miracle I didn’t go off the rails before I did. It took three or four years – and my discovery of cocaine – before things started getting out of hand, maybe because I was working so hard that I didn’t have too much time to think about it. I was always on tour or making a new album. Of course, when I did go off the rails, that happened like a missile as well.

It’s strange, I don’t find it painful to watch those parts of the film. They’re truthful and, unlike my childhood, it was my own fault. No one forced me to do drugs and drink. In fact, more than a few people tried to warn me I was out of control. It took a fairly Herculean effort to get yourself noticed for taking too much cocaine in the music industry of 1970s LA, but I was clearly prepared to put the hours in.

I gave my diaries to Taron to read when he took on the lead role in the film. He came to my house, we had a takeaway curry and chatted, and I let him see them. I knew Taron was the right man when I heard him sing Don’t Let the Sun Go Down on Me. I thought it was really important that whoever played me didn’t lip-sync, I wanted them to actually sing the songs, and Taron had already sung I’m Still Standing brilliantly in the animated film Sing.

‘Welcome to my world, baby’: Taron Egerton as Elton John in Rocketman. Photograph: David Appleby

But Don’t Let the Sun Go Down on Me is a really hard song for a vocalist. I know, because I struggled with it myself. When I tried to record it in 1974, the session went incredibly badly: I just couldn’t get it right. Demonstrating my legendary composure and breezy good humour in the face of a crisis, I ended up threatening to strangle my producer Gus Dudgeon with my bare hands, then announced that the song was so terrible that I was never going to release it, and instead was going to give it to Engelbert Humperdinck. Taron, on the other hand, just sang it: no threats of murder, no mention of dear old Engelbert.

His singing really astounded me. He isn’t doing an impersonation of me, he doesn’t look uncannily like me – although they shaved his head and thinned out his hair to make it look like mine in the 70s, which he hated. Welcome to my world, baby – at least yours will grow back. But he’s like me, he’s captured something of me, just as Richard Madden’s got something of John Reid and Jamie Bell’s got something of Bernie.

‘Don’t get Bernie started on some of my more outlandish stage costumes’: in Sydney, 2001. Photograph: Bob King/Redferns

Jamie and Taron have even managed to capture my relationship with Bernie, which is frankly a miracle, because I really have no idea how that works. We were thrown together at random. I had failed an audition for Liberty Records in 1967, and a guy from the label gave me an envelope with his lyrics in it as an afterthought, like a consolation prize. I’m not sure he had even opened the envelope and read the lyrics himself before he did it: I think he just felt sorry for me and didn’t want me to go away empty handed.

We were very close right at the start of our career together, but we’re completely different people. He comes from the wilds of Lincolnshire, I come from the suburbs of London. He lives in Santa Barbara and he’s literally won competitions for roping cattle. I collect antique porcelain and the only way you’d get me on the back of a horse is at gunpoint. Neither of us can write if the other is in the room. But there’s a weird bond between us that I felt the minute I opened the envelope – I could just write music to his words straight away, without even thinking about it – and it’s lasted over 50 years.

We’ve had arguments – you don’t want to get him started on the subject of some of my more outlandish stage costumes, or indeed the subject of Don’t Go Breaking My Heart, a song he’s loathed from the minute it was finished and continues to loathe to this day – but we’ve never fallen out, despite all the ridiculous crap we’ve been through.

‘Bernie never gave up on me’: John and Taupin at the 27th Annual Elton John Aids Foundation Academy Awards viewing party, West Hollywood. Photograph: Michael Kovac/Getty Images for EJAF

Outside of my husband and children, it’s the most important relationship in my life, we really love each other and the film captures that. There’s a scene in Rocketman where he comes to visit me in rehab, and that started me sobbing again. It happened just the same way in real life. Bernie was one of the people who tried to tell me to stop doing drugs. I wouldn’t listen until years later, but he stuck by me, he never gave up on me, and he was so relieved and happy when I finally got help.

He was apprehensive about the film. He read the script and he didn’t like the fantasy aspects of it. “But that didn’t happen, that’s not true” – very Bernie. Then he saw it and completely got it. I don’t think he actually burst into tears, but he was incredibly moved by it. He understood the point of it, which was to make something that was like my life: chaotic, funny, mad, horrible, brilliant and dark. It’s obviously not all true, but it’s the truth.

Rocketman is in cinemas now