Cathy Moriarty has never seen Raging Bull. “I mean, I’ve seen parts of it,” she says. “Just not in its entirety. Not in one sitting.” This is astonishing: Moriarty’s performance as Vikki LaMotta, wife of feral boxer Jake, is unforgettable. It is, of course, a savage film – but that’s not why she avoided it.

“It was the first time I’d heard my voice recorded,” she explains. “The film played and I said, ‘Who is that?’ They said, ‘It’s you.’ And I said, ‘That is not what I sound like. That sounds like a truck driver.’” The voice remains a wonder: a rasping aide-memoire of old New York. “I like it now,” she says. “It just took me a while.”

Martin Scorsese’s 1980 film captured her in timeless black and white, in a masterpiece for her first role. Now 54, she is still a presence, strikingly tall, honey blonde hair. And it’s not just Raging Bull: she’s never seen most of the films she’s made. “They make you sit through some – but you can always go to the bathroom.”

The latest movie in her strange, stop-start career won’t leave her much time to make an exit. It’s a 15-minute short called Outlaws, made for the British luxury sportswear label Belstaff. As evidence of modern marketing budgets, a cast including Moriarty and Harvey Keitel decamped to Mexico to appear in a stylised stew of freak show and biker imagery. The star, however, is David Beckham, asked to brood silently in a £1,000 leather jacket. Playing an earthy waitress – the kind of part she gets a lot these days – Moriarty is excellent. She talks gamely about the pleasures of working with Beckham, a “gem” whose kids bonded with hers; she has 15-year-old twins and a 14-year-old daughter. One of the twins is here today, a dark-haired girl introduced as little Cathy, who mostly stays glued to her phone. Little Cathy’s younger sister is, Moriarty says, “the artistic one, with the singing and the plays”. Would her mother be happy for her to act? She grimaces. “I’d support them. But there would be a conversation.”

Cathy Moriarty today. Photograph: David Levene for the Guardian

Moriarty was one of seven kids, born in the Bronx before moving to nearby Yonkers (“a little fancier”). Her parents were Irish immigrants; a branch of the family runs a bed and breakfast in Kerry. Her father worked as a warehouseman. As a child, she decided she wanted to act. “‘Big imagination,’ everyone said.” There was no money for drama school, so she put on shows outside her family’s home. “People said, ‘Be a nurse!’”

Her break is a famous story. “What version do you have?” she asks. The shoes, I say, and she nods. By 17, she was a regular at a Bronx nightclub called Hoops. She didn’t like the disco music they played. “But I could dance and it was the local hangout.” One Sunday night, the owners staged a bathing beauty contest. She agreed to enter provided that if she won she’d get a pair of shoes. “Black high heels with an ankle strap. They were the only reason I said yes.” It was 1978.

David Beckham in Outlaws. Photograph: Whit Lane

When she won, her photograph was pinned up at the bar. A few weeks later, a passing actor said she should send it to the casting director of a film he was making. His name was Joe Pesci. He said she looked like Vikki LaMotta. Moriarty sent the picture, then forgot about it. At the time, she was waitressing at a burger bar and working as a receptionist in Manhattan’s garment district. She was cast after three months of arriving at 5.30pm every day for read-throughs with Scorsese and Robert de Niro. She had a vague awareness of who De Niro was, though Scorsese had passed her by. Her tastes ran more to the golden age of Hollywood. “I did not have a clue. But I also had no fear: I was 17 and I was better than you.”

Filming took more than a year. “Bobby taught me to listen and that was important, because if there was a script on Raging Bull, no one used it. He was good to me. Joe and Marty, too. I knew people would look at these older men and this teenage girl like, ‘Oh, I get it.’ But they were gentlemen. They also yelled at me when I needed yelling at.” Did she yell back? “Of course.”

And then when it was over, she couldn’t watch herself. “But I was good, right?” She was great – and was nominated for a best supporting actress Oscar. The first chapter of a fairytale was written; the rest went haywire. She didn’t have an agent and, just before the awards, went to Europe on holiday. “Smart, right?” She lost to Mary Steenburgen in the comedy Melvin and Howard. It was the start of a pattern: decisions that backfired, sheer bad luck.

Determined to seize the day, she moved to Los Angeles, where Hollywood producers questioned her accent. “I didn’t even have an accent!” she says. “You people have accents!” There was also a snobbish suspicion of a working-class actor with limited experience. “People assumed I’d lived the life of Vikki LaMotta. I thought, ‘You know nothing about me.’”

Moriarty with Dan Aykroyd and John Belushi in Neighbors. Photograph: Snap/Rex Shutterstock

She knew she had to expand her range. The film she chose to do it with was Neighbors, a blighted comedy remembered only as the last film made by her co-star John Belushi before he died from a cocaine and heroin speedball. By then, she had married Carmine D’Anna, the owner of an LA car-repair business, and soon to be her manager. Today, with little Cathy present, she deals with the era briskly. The marriage, she says, was “a bad situation”. D’Anna found her no acting jobs. Mostly, she didn’t even get auditions. “I saw movies and thought, ‘Wow, I would have done that really good.’ And I didn’t even get to try.’”

Then, on a wet Thanksgiving night in 1985, there was a car crash. “It was bad. I was in a coma for five days. My back was broken. After that, you make decisions.” She was still only in her 20s and, after regaining her health, she mounted a comeback. She won a role in the horror movie White of the Eye, made by the infamous Donald Cammell, co-director of Performance (“a very odd man”). Soon, Moriarty was divorced.

From Raging Bull to Mambo Kings to Casper … scenes from Cathy Moriarty’s most well-known films – video

In the 80s, while not making movies, she took a stake in a West Hollywood sports bar. Later, there would be restaurants and nightclubs. Her most successful venture was co-ownership of the Mulberry Street pizzeria chain that began with one branch in LA. Early on, she worked front of house. She was a natural maître d’, she says: “It’s acting. You’re selling a character. Hello!” She beams, poised to usher me to the breadsticks.

The business gave her a cushion as she went back to acting. Many jobs came in the sort of indie movie where “by the time it comes out, it’s cost you money”. The most high profile ones – the thriller Cop Land and mob comedy Analyze That – reunited her with De Niro.

Moriarty with Sally Field and Whoopi Goldberg in Soapdish. Photograph: Moviestore/Rex Shutterstock

Then, in 1999, she married Joseph Gentile, a New York property developer. Back on the east coast, they had three children in the space of a year. Gentile began his career working for developer Fred Trump, father of the current presidential candidate. “I like Donald,” she says. “I’m not saying I’m voting for him.” She doesn’t often talk politics, she says. The conversation shifts, as it often does, to her kids. “God, family, self, that’s how I see it.”

She says she’s “old and fat now”. Before I can interject, she adds: “But the kids are teenagers and I’m ready to work.” I mention her role in The Double, in 2013, and she looks blank. How about Richard Ayoade, its director? “Richard! How much do we love him?” There’s another pause. “Is it good?” Yes, I say – you should see it. “When I do a comedy,” she says, “I might watch it. Otherwise, it’s too personal. I like doing them. But once it’s done, I’m done.”

Sometimes, she says, she can be parking her car and she’ll remember a line she said in a film and suddenly be mortified. “I think, ‘Aaah! Why didn’t I say it that way?” What, a few days after shooting? “Oh no,” she says. “Like, 10 years later.”

• Outlaws can be seen at belstaff.com.