On Tuesday, Lattanzi, 36, shared footage on Instagram of her and Newton-John, who died at age 73 on Monday, while they recorded their 2021 duet "Window in the Wall," which the pair released as a single in January 2021.
The footage shared by Lattanzi shows the close bond she shared with Newton-John, with the pair almost always shown standing or sitting right next to each other when they are on camera.
"You are my lighthouse mama. My safe place. My heart space," Lattanzi wrote in the post's caption. "It has been my honor and continues to be my honor to be your baby and best friend. You are an angel on earth and everyone touched by you has been blessed."
"I love you forever my life giver, my teacher, my mama," Lattanzi added.
"Window in the Wall" debuted at the top of the Billboard Pop Music Video chart in January 2021 and first came to Newton-John's attention by email from a woman she had met years ago, she told PEOPLE in February 2021.
"Out of the blue, she sent me an email saying, 'I found this song, and I think you need to sing it,'" she told PEOPLE, adding that she felt an instant tinge of dread. "I thought, 'Oh gosh, I know it's not going to be good. How am I going to tell her?'"
Sam Tabone/WireImage Chloe Lattanzi and Olivia Newton-John
But when she listened to the song for the first time, she was on board.
"It moved me to tears," she told PEOPLE at the time. "It's a very healing song. I thought, 'This is very special, and I want to sing it with Chloe.'"
When Newton-John asked Lattanzi to join her on the track, she responded, "Yes — no questions asked."
Never miss a story — sign up for PEOPLE's free weekly newsletter to get the biggest news of the week delivered to your inbox every Friday.
"I was flattered and honored," Lattanzi said. "She could have asked anyone, and she asked me. That meant the world to me. It's my dream job — I get to spend time with my favorite person."
"There is always something special about singing with my daughter," Newton-John said in a press release at the time. "She not only has a gorgeous voice, she's an amazing musician with tremendous instincts as a singer."
Lattanzi later told PEOPLE of the collab: "I was flattered and honored. She could have asked anyone, and she asked me. That meant the world to me. It's my dream job — I get to spend time with my favorite person."
On Monday, Lattanzi posted a series of sweet photos with herself and the Grease star just hours after Newton-John's death was announced. The photo series begins with a throwback of Lattanzi adorably grabbing her mother's face for a kiss and ends with selfies and photos of the mother-daughter duo throughout the years.
In May 2017, the four-time Grammy winner shared that she was diagnosed with metastatic breast cancer that had spread to her back.
"I'm so lucky to still be doing all these things," Newton-John told PEOPLE of attending Lattanzi's wedding and releasing "Window in the Wall" at the time. "I don't think I imagined living this long! I feel very blessed."
Though they always shared a tight bond, Newton-John and Lattanzi became even closer as they quarantined together in California during the coronavirus pandemic. Lattanzi eventually moved to Portland, Oregon, but revealed in late July that she had moved back to be near Newton-John.