Kelli O'Hara speaks to PEOPLE about working with Ruthie Ann Miles in The King and I after she had suffered the devastating double loss of her unborn child and her 5-year-old daughter

Kelli O’Hara continues to be inspired by the strength of her friend, Ruthie Ann Miles.

The actress opened up with PEOPLE about returning to the stage to work alongside Miles in the London production of Rodgers and Hammerstein’s The King and I over the summer — a gig that came just months after Miles had suffered the devastating double loss of her unborn child and her 5-year-old daughter.

Their performance in the classic show was filmed for The King And I: From the Palladium, which was screened in movie theaters worldwide on Thursday (More screenings are scheduled for Dec. 4).

“I’m in such awe of her,” O’Hara, 42, said in September, weeks before the 14-week limited run wrapped up. “I think it’s good that she’s here.”

Both friends earned Tonys for their performances in the musical back in 2015, when the Bartlett Sher-helmed revival was at Broadway’s Lincoln Center Theater. But Miles’ tragedy helped O’Hara’s see her reason for returning was bigger than she originally thought.

“My purpose for being here is to be here for [Ruthie],” O’Hara added. “And that is the only goal.”

"The King And I" Opening Night
Ruthie Ann Miles and Kelli O’Hara
| Credit: Jenny Anderson/WireImage

In March, Miles — who was seven months pregnant at the time — was injured and her 5-year-old daughter, Abigail Blumenstein, was killed when a driver struck them in Brooklyn, New York. Her unborn child died two weeks later.

The driver, Dorothy Bruns, also struck and killed 1-year-old Joshua Lew and injured his mother, Miles’ friend Lauren. Bruns, who was charged in their deaths, has since died by suicide.

The King and I audiences praised Miles back in August when she took the stage for the first time, many praising her on social media for her “unspeakable bravery, rawness, and brilliance.”

O’Hara was one of them. “Last night, our friend @RuthieAnnMiles was a triumph in @KingandIWestEnd,” she wrote. “Every moment was a gift and continues to be.”

She is singing like an angel and commanding the stage with a heavenly force. An inspiration to all. I knew you would want to know.”

Ruthie Ann Miles in The King and I
| Credit: Paul Kolnik

The emotions surrounding Miles’ return was one of the things that made The King and I feel like a new experience for O’Hara.

“Things are definitely different in 2018 than they were in 2015,” she said. “It feels different in many ways, just as far as emotion. We’ve had a lot of personal things happening here within our run. It’s made the experience all that more rich and purposeful. If you have a good reason to do it and do it in a new way, that makes it feel really right. And that’s what I’ve felt here.”

Ultimately, O’Hara described doing The King and I as”one of the more fulfilling things I’ve ever done in my career.”

2018 Tony Awards - Red Carpet
Kelli O’Hara
| Credit: Dimitrios Kambouris/Getty

As a mother of two herself, she remarked on how playing Anna — an 1860s British schoolteacher who brings her son to Bangkok to teach King of Siam’s wives and children — impacted her.

“When I started to play Anna, I didn’t think about it. I thought, ‘Oh gosh, I’m going to do that musical. That’s a lead role. That’s a good strong woman. She’s a mother first. She’s vulnerable, she’s a self-preservationist and needs to support herself and her child.’ But you don’t realize how much it does affect your life and how things kind of fall into place in a way,” O’Hara said. “You can look for purpose and signs everywhere and if you do, you see that when you play someone like Anna, you start to believe in yourself a little bit more. Your back is a little straighter. You think of yourself as a, ‘Maybe I am a good mom? Maybe I do have something to say? Maybe I do really believe in the love of a marriage that could last even once the spouse is gone?”

“Things like that, they seeped into my life,” she continued. “And even though some people come to the show and see a really lavish set, and beautiful score, and adorable children and love it, there are these really deep things that run through my mind every single night.”

The King and I_London_13_Image credit © Matthew Murphy
Kelli O’Hara and Ken Watanabe in The King and I
| Credit: Matthew Murphy

And knowing audiences around the world will now have the chance to see this live performance on film?

“It makes me nervous, but it’s also thrilling,” O’Hara explained. “I’m born and raised in Oklahoma. I didn’t have any live theater as a kid, and I fell in love with this profession through movie musicals. If I hadn’t had those examples, I wouldn’t have explored it in high school, gone to school for it, moved to New York — it all stemmed from being able to actually see it happening on my screen.”

“If one kid like out in the middle of somewhere like me says, ‘Gosh, whatever that art form is I want a part of it. I want to go to a place to do it or I want to create it here in my small town theater’? Well then I think we have to do it.”

For showtimes to The King and I: From the London Palladium, click here.