After a successful career spanning nearly four decades, this will surely be the glittering highlight. Gary Oldman is considered almost unbeatable in the race to be crowned Best Actor at next month’s Oscars ceremony thanks to his superlative performance as wartime leader Winston Churchill in the £25 million drama, Darkest Hour.

His on-screen transformation into Churchill, whose stoicism and courage guided Britain through its lowest ebb, has been described as remarkable and few critics think the 59-year-old will go home empty-handed on March 4.

But if for Oldman, the son of a South London welder, this is the fulfilment of a lifelong dream, there is one woman who will not be joining the expected billion-strong global audience to cheer him on – even though she is the mother of two of his children.

For while Oldman’s sons Gulliver, 20, and Charlie, 18, are expected to join their father on the Oscars red carpet, Donya Fiorentino, the third of his five wives, will be elsewhere that night. And with good reason.

While Oldman’s sons are expected to join their father on the red carpet, Donya Fiorentino, the third of his five wives (pictured near her Florida home), will be elsewhere that night

Living quietly on a 50ft houseboat in the Florida Keys, Donya, 50, has never before spoken about what she calls the ‘nightmare’ of her four-year marriage to the star, a dark time which ultimately exploded in a furious court battle featuring an accusation that Oldman beat her up with a phone while she held their younger son.

In devastating legal documents filed in 2001, Donya painted the actor as a deadbeat husband who spent thousands on alcohol and prostitutes during drug-fuelled weekends – charges Oldman vehemently denied.

In reply, he called his former wife a ‘fantasist’ whose own raging addiction to pills and alcohol tore apart their marriage and left her an unfit mother. It is certainly true that a judge eventually sided with Oldman, granting him custody of their young sons.

Since their divorce, Oldman has become one of Britain’s most successful exports to Hollywood, starring as Harry Potter’s godfather Sirius Black in the hit films and in blockbusters such as Batman Begins and The Dark Knight, while earning plaudits for his performances in movies such as JFK and Tinker Tailor Soldier Spy.

Now Donya, a former model, has decided to break a vow of silence about her former husband, because, she says, she wants the world and her children to know the reality about the man behind the slickly managed Oscar campaign – a man she claims abused her physically and emotionally before using his fame, power and money to gain custody of their sons.

‘He stole my children and ruined my life,’ she told The Mail on Sunday, tears rolling down her cheeks. ‘The truth needs to be told. I would like Gary to stand up and take responsibility for his actions. Will he? Who knows? He has always denied everything.’

Gary Oldman and Donya Fiorentino arrive for a premiere in London with Oldman's mother in 1997. They married that year and divorced in 2001

Emboldened by the #MeToo movement sweeping Tinseltown – which has already claimed the careers of sexual predators such as Harvey Weinstein – soft-spoken Donya said last night: ‘He is a great actor. Was he a great husband? No.

‘Our marriage was a giant car crash in which demented things happened. I lost my self-esteem, I was broken.

‘I’ve been empowered by hearing other women speak up. When a woman gets her voice back, she gets her power back.’

Donya says it took ‘all the courage I have’ to give this interview.

Staring over the crystal-blue waters off the Florida Keys, she says: ‘I want our sons and the world to know the truth. I would rather get eaten by a great white shark than go through that marriage again.

‘I have $20 in my purse. I’ve got nothing else he can take from me. I’m not speaking out to hurt Gary. In fact, I wish him well. He’s a brilliant actor and he fully deserves his Oscar. But when you are nominated for an Academy Award you have to be held to a higher standard.’

Donya’s dark good looks had captured the hearts of Wham! star Andrew Ridgeley and Fight Club director David Fincher (her first husband) when she caught Oldman’s eye across the room at an Alcoholics Anonymous meeting in Hollywood in 1996.

Oldman was a rising star thanks to Dracula, The Firm and JFK, but his off-screen antics were already causing whispers. In 1991, he was arrested for drink-driving alongside another notorious ‘party boy’, 24 star Kiefer Sutherland.

Donya, a former model, has decided to break a vow of silence about her former husband, because, she says, she wants the world and her children to know the reality about the man behind the slickly managed Oscar campaign

‘I think it’s fair to say we were not the most stable people in the room,’ Donya says.

‘I was three years sober when we met. He was a newcomer to AA.

‘I had never met someone so fragile, so emotionally vulnerable. He was charming and I thought I could fix him.

‘He invited me to dinner at The Ivy in Hollywood. That night he told me he wanted me to have his son. He wanted to call him Gulliver after the character in his favourite book, Joyce Cary’s The Horse’s Mouth.

‘We fell in love quickly – too quickly. We didn’t know each other. We’d married strangers.’

Donya, who already had a two-year-old daughter, Phelix, with Fincher, was pregnant with Gulliver when they married just four months after that first date.

Oldman’s relationship history was as turbulent as his social life. His first wife, British actress Lesley Manville is, ironically, also up for an Oscar this year as supporting actress in Phantom Thread, which stars Daniel Day-Lewis.

Kill Bill star Uma Thurman was his second wife, and he was at the end of a passionate affair with Blue Velvet actress Isabella Rossellini when he met Donya, a successful model who had fronted campaigns for Revlon and appeared in music videos for Van Halen.

Oldman has been sober for more than 15 years but makes no secret of his former hell-raising. He told one interviewer he would check into New York’s Carlyle Hotel on four-day benders. ‘I’d go through the fridge three, four, five, six times,’ he admitted.

Gary Oldman and Donya Fiorentino are pictured with their son Charlie John. Their relationship soured when Donya was diagnosed with rheumatoid arthritis during her second pregnancy

But his marriage to Donya was, she claims, fuelled by their combined addictions which left Oldman ‘deeply depressed’, particularly as Oscar season came around. ‘His career was stalled when we were together and every awards season he got depressed. He would sleep all night with me then sleep all day downstairs on the sofa.’

The pair lived in Oldman’s £7 million Hollywood Hills mansion with Gulliver, and the actor’s mother, Kathleen, who moved over from the UK to help with the growing family.

There were some happy times.

‘Kathleen taught me to make his favourite Yorkshire puddings,’ Donya recalls. ‘He loved PG Tips. After Gulliver was born he wheeled me out of hospital and said he couldn’t wait for us to have a second child. When I was pregnant with Charlie he would kiss my swollen belly.’

But their relationship soured when Donya was diagnosed with rheumatoid arthritis during her second pregnancy.

‘I was in pain. I couldn’t cope,’ she continues. ‘Gary yelled at me constantly, saying other mothers coped without any problems. I became angry and resentful.’

Charlie, named after Charlie Bucket from Willy Wonka And The Chocolate Factory, was born in 1999. Oldman was, Donya admits, great with the kids, watching Chitty Chitty Bang Bang with them, and doing Charlie Chaplin impressions. But it was the beginning of Donya’s downfall, spiralling into addictions to painkillers and alcohol.

The pair had furious rows. Donya says: ‘He would say I married him because he was rich and famous – but I married him for love.’

She claims the rows sometimes erupted into physical violence. In legal documents, after Donya filed for divorce in 2001, she alleges Oldman beat her with a telephone receiver as she cradled Charlie.

Oldman married his fifth wife, Gisele Schmidt, last year after proposing in his full Churchill outfit for Darkest Hour (pictured)

‘I tried to dial 911,’ the papers say. ‘Gary grabbed the receiver from my hand and hit me in the face with it three or four times.’

They continue: ‘Gary told me there had been times when he’d spent over $18,000 in a weekend at hotels in New York, drinking several bottles of vodka, whisky and wine per day, paying for prostitutes, his hotel room and drugs.’

For his part, Oldman claimed Donya, too, had major problems with drugs and alcohol abuse and, ultimately, he won legal custody of the children. Donya had twice-weekly visits, and access to them every other weekend.

The bitter divorce, and the marriage, remains a painful memory.

‘It happened a long time ago but it was incredibly traumatising to me because he hit me in front of the kids,’ she says.

‘The kids were held hostage in the war between us. I eventually ran out of money and was representing myself in court. Money, power and fame won. I will take blame, I played a big part in destroying my life and that is something I have to live with. I am sorry I was not the mother I should have been.

‘I don’t blame Gary for everything. But it takes two to destroy something. The perpetrators of domestic abuse have to live with it too.’

At times, she admits, it was right for the children to be with Oldman. One memory is particularly painful – the Christmas the boys were eight and nine, immediately after she had been discharged from hospital following back surgery.

‘I got out of hospital on Christmas Eve. I had the boys on Christmas Day and I didn’t have any decorations or a tree or presents,’ she recalls.

‘I had been in hospital for months. I couldn’t do anything, I didn’t have a housekeeper or chef like Gary. The boys held that against me. Yet looking back, all the time I was ill, Gary never once bought the boys to hospital to visit me.

‘Ten years ago I was driving along Melrose Avenue in Los Angeles and I did a U-turn in traffic into a car park. There was Gary, smoking a cigarette.

‘I was stunned because I had not seen him, outside a court room, in so many years. I wound down the window and asked him if I could see my sons. He just said “No” and turned the other way. It was all I could do not to cry. I felt I’d been punched in the heart.’

She is now working on rebuilding her relationship with her sons.

Oldman has two more marriages under his belt since his divorce from Donya. His fourth, in 2008, was to Somerset-born jazz singer Alexandra Edenborough, and he married his fifth wife, Gisele Schmidt, last year after proposing in his full Churchill outfit for Darkest Hour.

Recent publicity for the film has reopened old wounds for Donya. ‘I am talking now not because of Gary but because I want my children to understand what happened. I’ve moved on with my life but that’s not to say it doesn’t still hurt. ‘I wish him well. I truly do. A lot of water has passed under the bridge.’

Donya hopes she will inspire others to speak out.

‘I’ve lived with my demons for years but the truth will always come out. I hope Gary has faced down his demons. My hope for him is that he has achieved the peace and calm we never had.’

Additional reporting: Annette Witheridge in the Florida Keys