Warning: Contains *huge* spoilers for the ending of A Star is Born.

Anyone's who seen A Star is Born will know that the final song in the movie is by far the most gut-wrenching and emotional moment.

Lady Gaga sings "I'll Never Love Again" — a song written about her by her late husband Jackson Maine (Bradley Cooper) — in tribute to him. It's a powerfully moving moment that reduces you — and everyone else in the cinema — to a sobbing wreck.

Lady Gaga has shared a personal story about the day that scene was filmed and the reason that scene was so important to her. Right before filming the scene, Gaga received a phone call that her best friend Sonja Durham was about to pass away from stage IV cancer.

SEE ALSO: Lady Gaga pens touching note for her late best friend

"On that day my friend Sonja — who had been battling cancer for years — her friend called me and I could hear her moaning in the background and she said she's not doing well," Gaga told Zane Lowe. "And I thought she was dying so I left the set.

"I didn't even stop to go see Bradley [Cooper], I just got in my car and started driving and I missed her by 10 minutes," she continued.

"I didn't even stop to go see Bradley, I just got in my car and started driving and I missed her by 10 minutes."

Gaga says she lay with her friend's widower and her stepson for some time before saying to them that she didn't know what to do. "He said 'you've gotta do what Sonja would want you to do,'" Gaga said. "She gave me a tragic gift that day and I took it with me to set and I sang that song for Jackson and for her on that very same day within an hour."

Gaga said that Cooper was very kind to her when she returned back to the studio to film the final song.

"Bradley was so beautiful with me that day, he was so loving. He was like, 'You don't have to do it too many times, it's ok.' And, I was like, 'All I wanna do is sing, man.'

"Life is hard man, but we've gotta stick together. What's more important than any of this, the fame, the accolades? What's important is the process of love and kindness," said Gaga. "I think the star of this film is human courage, bravery."