My kids Maddox and Pax saw my pain on the set of Mariah

Angelina Jolie is known for her privacy.

But in a new interview with BBC News, the Hollywood star spoke frankly about her experience working with her eldest children, saying they saw the “pain” she usually hides from them.

The actress stars in a new biopicTitled Maria, it is about the opera singer Maria Callas.

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

“(Callas)'s character is in a lot of pain, and of course they've seen me go through a lot of things, but they haven't experienced me expressing a lot of pain that a parent usually hides from a child.” He said.

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

Jolie added that it was a “new way” to learn how to be honest with her children about her feelings, “in a greater way.”

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

Since Jolie has taken on relatively infrequent acting roles in recent years, the film offers her something of a comeback story and could lead to her being nominated for an Academy Award for Best Actress.

Callas was an American-born Greek soprano and one of the most famous opera singers.

In Maria, a combination of Julie's voice and Callas's original recordings are used in the singing scenes.

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

She said the training took about seven months.

“We started with regular singing classes and it was difficult in a lot of ways, but when I started opera classes, what it took from your breathing and your body and the force of what you were pushing through yourself, it was just a completely different physicality.”

Jolie, whose previous film credits include Changeling, Maleficent, Salt and Mr & Mrs Smith, said she had never sung before and was “actually quite shy about singing”.

“This was probably one of the areas in my life that I was hesitant about,” she said.

But she noted that it was also something she enjoyed.

“One of the greatest privileges of being an actress is that you are often supported by a crew to try something and explore something you haven't done before, and this was definitely the most challenging,” she said.

Jolie's sons Maddox (23 years old) and Pax (21 years old) have worked with her on a number of works before, including her film “Without Blood.”

They both accompanied her to the premiere of Mariah in New York City in September, alongside their younger sister Zahraa.

Jolie filed for divorce from Pitt in September 2016. The couple had entered into a custody battle that led to Pitt's death. Joint custody awarded in 2021.

The Hollywood stars also have two daughters, Shiloh and Vivienne, and another son, Knox.

Director Pablo Larraín said that on the film's set, both Maddox and Pax were “very busy.” “They were good professionals,” he added.

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

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

“So this is an important and beautiful thing.”

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

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

“Jolie is absolutely stunning as Maria Callas, bringing grace and determination to her.” said Sophia Ciminello of AwardsWatch. “She doesn't disappear into the role, she excels.”

Time magazine's Stephanie Zacharek was less keen However, regarding her performance, she said that Jolie “plays her as cool, arrogant and very insecure, but she doesn't capture any of her domineering charm.”

Maria Callas, nicknamed La Divina, began singing at the age of fourteen.

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

But vocal decline, possibly caused by drastic weight loss, led to a premature end to 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 hopes his film honors Callas' desire to popularize the art form.

“If this film attracts attention to the opera from 1 to 100 to a 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 you connect with spirit and body is, of course, for everyone.”

Maria will be released in UK cinemas on January 10.