Gaga's emotional tribute to friend 

Singer Lady Gaga has written an emotional tribute to her longtime friend and former assistant Sonja Durham after learning that she has passed away after battling cancer for a long time.Gaga shared a heartfelt message on Instagram on Friday alongside a photograph of her with Durham, reports mirror.co.uk.

"Watching one of my best friends in the world show unfathomable courage, strength, and positivity while battling cancer has really changed my life," Gaga wrote."Thank you Sonja for inspiring me and all of us everyday with your joy. I love you so much it brings tears to my eyes just to think of all the years we've spent together backstage running the show, taking care of each other. You are one of a kind. I'm so proud of you," she added.Durham was battling cancer since last five years.