Delta Goodrem Says Olivia Newton-John Sent Her a Touching Letter After Her Own Cancer Diagnosis

Delta Goodrem is hopelessly devoted to Olivia Newton-John.

The Australian singer and actress plays the iconic Grease star in the new biopic about her life, Olivia Newton-John: Hopelessly Devoted to You, premiering on Lifetime on Saturday — and she says it was a total full-circle moment.

“I, kind of, have been preparing my whole life to play her,” Goodrem, 34, tells PEOPLE. “When I got signed to Sony Music when I was 15 years old and they said, ‘Who do you want to be when you grow up?’ I said, ‘Olivia Newton-John.’ Then, it literally happened. It took 15 years, but it did end up being a part of the journey.”

Olivia Newton-John: Hopelessly Devoted to You tells the remarkable personal and professional journey of the 70-year-old Australian star. Covering her life across five decades, the film delves into both Newton-John’s public persona as well as the private woman behind-the-scenes, including her multiple battles with cancer and her fight to survive.

“Olivia is the same person on camera as she is off,” Goodrem says. “I get that, me too. [She’s] authentically being herself at all times and doing it for the right reasons.”

Since Goodrem and Newton-John are close friends, Goodrem says she only decided to accept the role — which sees her recreating Newton-John’s iconic on-screen moments from films like Grease andXanadu, as well as her “Physical” music video — after getting Newton-John’s blessing.

“There were so many conversations,” she says. “When Olivia said to me, ‘I really want you to play the role and do it,’ I thought, ‘Okay, well I’ll give it all my heart and soul and take on the role.’ It felt very special, and I felt very protective over this role.”

Though Goodrem and Newton-John first collaborated in 2008 when they wrote and recorded a song together called, “Right Here With You,” Goodrem says they had met years prior when she was only 7 years old and on a trip to New York.

“I was having a hot chocolate with my mom and Olivia walked into the place that my mom and I were at in New York,” Goodrem explains. “All of a sudden, I started freaking out, like, ‘Oh my God, it’s Olivia! Sandy from Grease is walking past!’ Basically, Olivia heard me speaking because I was clearly not as subtle as I thought I was. My mom was saying, ‘Stay cool, stay cool, Delta.’ I said, ‘Sandy! Sandy!’ She came over to the table and said, ‘You’re Australian.’ I said, ‘Yes we are, we’re here on holiday.'”

Newton-John chatted with Goodrem and her mom before saying, “Well I hope I’ll see you around tomorrow.”

“That next day, I was looking everywhere in New York for her,” Goodrem continues. “I thought, like, ‘I’m going to find Olivia Newton-John! She wants to see me today!’ That was our first meeting, and then as time went on, I was backstage a lot as a kid due to record labels and we had crossed paths.”

She adds: “Little did we know we’d be a big part of each other’s lives later on.”

Goodrem and Newton-John’s bond really cemented after Goodrem was diagnosed with Hodgkin’s lymphoma in 2003 at the age of 18 years old. Several years earlier, Newton-John was first diagnosed with cancer in 1992 and underwent a partial mastectomy, nine months of chemotherapy and a breast reconstruction.

“She sent me a letter when I got diagnosed with cancer and she said beautiful words and told me that, ‘One day, you’ll see this is a gift and understand to give back and let people know you can be a tower of strength,'” Goodrem says. “So that was my next beautiful letter from her. Then we ended up writing songs together for her album and for her charity [so] that was the start of our friendship.”

Goodrem’s diagnosis came at a time when her career was starting to take off and in the middle of her debut album being released.

“I went from planes, trains and automobiles to my whole world [being] hematologists and oncologists,” she says. “I began the fight. That’s life. I was surrounded by beautiful family and the whole country and we had special moments — I’ll never forget Elton John calling me on my first day of chemotherapy and saying, ‘On behalf of Britain, we hope you feel better.’ It was a pretty extraordinary time.”

Hearing the news that Newton-John’s cancer had returned and that she was diagnosed with stage 4 breast cancer that had metastasized to the sacrum in May 2017 was understandably difficult, but Goodrem says that Newton-John is a “thriver” at all times.

“The fact that she’s, right now, on the road to recovery and she’s staying on schedule and she’s coming back with a book tour in March is incredible,” Goodrem says. “She’s so positive and stands there as a warrior. That’s what I think you learn in the biopic, you realize that through everything that happens to her, she wants to make sure that other people remember to fight. There’s a reason for everybody knowing about what she goes through in music or anything so that she can bring good and make a difference in the world.”

RELATED: Olivia Newton-John Is Recuperating from Cancer Treatments with Herbs and Cannabis: Source

Newton-John’s most recent diagnosis is her third bout with cancer, which some doctors describe as incurable but capable of being managed through treatment.

Not only can Goodrem and Newton-John bond over their similar backgrounds and battles with cancer, but also their love of music. The Voice Australia coach re-recorded Newton-John’s classic hits for the movie’s soundtrack, I Honestly Love You, which also includes two duets recorded with Newton-John called “Let Me Be There” and “Love Is A Gift.”

“When we got to have that moment singing these songs, instead of being the artist, I was the young girl with the dream who was standing there opposite my idol and it made me very emotional and very teary-eyed,” Goodrem says. “It’s a lot of fun, but it was very cathartic and very beautiful — a moment I will remember forever.”

“We love singing together,” she continues. “I wanted the soundtrack to sound very classic and timeless to her original, because why would you paint over something so beautiful already? Having her involved and being there with the soundtrack was really fun.”

Another aspect of the film is that it depicts the toll that Newton-John’s booming career took on her earlier romantic relationships with ex-husband Matt Lattanzi and ex-boyfriend Patrick McDermott. Goodrem’s own career has affected her relationships because of the heightened interested in her personal life, and it seems that new tabloid stories come out every week in her native Australia claiming that she’s either pregnant or married.

“I’m starting to get confused,” Goodrem says with a laugh. “I’m like, wait, I’m pretty sure I’ve never been pregnant or had a beautiful child. While I look forward to that chapter one day in my life, right now I’m very much with my music and with acting and with the art.”

“I understand that there’s always going to be an interest in my personal life, and I appreciate that people are interested,” she adds. “I’ve learned along the way what to keep private when I know that I’m here to give with my music and acting. I used to be quite stressed and think, ‘Oh goodness me.’ But now I’m actually quite entertained by these storylines that are just not in alignment. But I don’t want to get in the way of anyone’s good story. The only people who get more angry are my friends who are disappointed about not being invited to any of these events.”

Olivia Newton-John: Hopelessly Devoted to You airs on Feb. 16 at 8 p.m. ET on Lifetime.