My children Maddox and Pax saw my pain on the set of Maria

Angelina Jolie is notoriously private.

But in a new interview with BBC News, the Hollywood star opened up about her experience working on set with her eldest sons, saying they saw “the pain” she usually hides from them.

The actress is starring in a new biopicwith the title Maria, about the opera singer Maria Callas.

Two of Jolie’s six children with ex-husband Brad Pitt, Maddox and Pax, took on roles as production assistants on the film.

“The character (Callas) is in a lot of pain, and obviously they’ve seen me go through a lot, but they hadn’t seen me express a lot of the pain that a parent usually hides from a child,” she said.

“So they were there to witness some of it, but then we’d hug or they’d bring me cups of tea.”

Jolie added that it was “a new way” to figure out how to be honest with your children about your feelings, “in an even better way”.

Written by Peaky Blinders creator Steven Knight, the film focuses on Callas’ final years, in the 1970s, when she lived in Paris.

With Jolie relatively rarely taking on acting roles in recent years, the film has provided something of a comeback story for her and could lead to an Oscar nomination for Best Actress.

Callas was an American-born Greek soprano and one of opera’s best-known singers.

In Maria, a mixture of Jolie’s own voice and original recordings of Callas are used in the singing scenes.

The actress learned to sing opera for the role, something she describes as “very physically demanding”.

The training took about seven months, she said.

“We started with regular singing lessons and it was challenging in a lot of ways, but when the opera lessons started, what it takes with your breath and your body and just the power of what you’re pushing through yourself, it’s just a very different physicality.”

Jolie, whose previous film credits include Changeling, Maleficent, Salt and Mr & Mrs Smith, said she has not sung before and was “actually quite shy about singing”.

“It was probably one of the areas in my life where I was hesitant,” she said.

But she indicated that it was also something she enjoyed.

“One of the greatest privileges of being an actor is that you’re often supported by a crew to try something and explore something you’ve never done, and it was certainly very challenging,” she said.

Jolie’s sons Maddox, 23, and Pax, 21, have previously worked on a number of productions with her, including her film Without Blood.

Both accompanied her to the premiere of Maria in New York in September, along with their younger sister Zahara.

Jolie filed for divorce from Pitt in September 2016. The couple were involved in a custody battle that resulted in Pitt being awarded joint custody in 2021.

The Hollywood stars also share daughters Shiloh and Vivienne and another son Knox.

On the set of the film, both Maddox and Pax were “very busy,” director Pablo Larraín said. “They were good professionals,” he added.

Jolie said that during filming, Pax recorded a lot of her singing exercises, “so he was with me in my early horrible days,” she laughed.

“It’s always good for your kids to see your mom not doing anything easy, but cursing and fighting and failing and having to try again,” she said.

“So it’s an important and beautiful thing.”

Maria is the third in a trilogy of films about high-profile, complex women from Larraín, following his films about Jacqueline Kennedy and Princess Diana.

The film has received mixed reviews, although critics have generally praised its central performance.

“Jolie is absolutely enchanting as Maria Callas, imbuing her with grace and determination.” said Sophia Ciminello of AwardsWatch. “She doesn’t disappear into the role, she transcends.”

The Times’ Stephanie Zacharek was less enthusiastic of her performance, but said Jolie “plays her subject as haughtily cool and deeply insecure, but captures none of her powerful charisma”.

Hailed as La Divina, “The Divine One”, Maria Callas began singing at the age of 14.

One of her most famous performances was as Tosca at Covent Garden in 1964.

But vocal decline, possibly caused by dramatic weight loss, led to the premature end of her career.

She spent her final years living largely in isolation and died of a heart attack at the age of 53.

Larraín said he hoped his film honored Callas’ desire to popularize the art form.

“If this film brings awareness to opera from one to one hundred to one million, it will be a success,” he said.

“I don’t know if there is an art form as powerful as opera,” Jolie added.

“The way it connects to the soul and the body, so of course it’s for everyone.”

Maria opens in UK cinemas on 10 January.