Lady Gaga is mourning the loss of her “real true friend” and collaborator, Tony Bennett, who died on July 21 at the age of 96.

In a lengthy and deeply emotional post on Instagram, Gaga opened up about “grieving the loss of Tony for a long time” as she watched his quality of life deteriorate due to Alzheimer’s disease.

“I will miss my friend forever. I will miss singing with him, recording with him, talking with him, being on stage together. With Tony, I got to live my life in a time warp. Tony & I had this magical power. We transported ourselves to another era, modernized the music together, & gave it all new life as a singing duo. But it wasnt an act. Our relationship was very real.”

Gaga and Bennett first worked together in 2011 for Bennett’s Duets II where the two performed “The Lady is a Tramp.” After their collaboration they became close friends.

The two worked together again for her 2014 Cheek to Cheek album, and once again for the final time in 2021 for Bennett’s Love for Sale album, which earned him his final Grammy in 2022.

But their relationship wasn’t just about music, Gaga explained.

“Sure he taught me about music, about showbiz life, but he also showed me how to keep my spirits high and my head screwed on straight. ‘Straight ahead,’ he’d say. He was an optimist, he believed in quality work AND quality life,” she wrote.

“Plus, there was the gratitude…Tony was always grateful. He served in WWII, marched with Martin Luther King Jr., and sang jazz with the greatest singers and players in the world.”