A former friend of Lady Gaga has penned an explosive tell-all book about his relationship with the singer and alleges she enjoyed "bags and bags" of cocaine. Brendan Jay Sullivan - who was close to the 27-year-old pop star while she was an aspiring musician in New York City - has penned an explosive memoir about his friendship with the 'Poker Face' hitmaker, in which he claims she enjoyed "bags and bags" of the illegal substance. In the new book, 'Rivington Was Ours: Lady Gaga, The Lower East Side and the Prime of Our Lives', Brendan alleges Gaga once brushed a mysterious white substance off the carpet at her Lower East Side apartment with her finger and proceeded to rub it into her gums. She supposedly said: "It's mint. I wish it was coke. I used to do bags and bags of it. Mostly when I was getting ready to go out, while I was putting on my make-up. "I'd get a delivery and then put on some Bowie and treat myself in the mirror. But I only ever did it alone. That was my one rule." The 'Edge of Glory' songstress has previously opened up about her illicit habit prior to finding fame in 2009, revealing that depression led her down a drug-fuelled path. She said: "I was very depressed when I was 19 ... I would go back to my apartment every day and I would just sit there. It was quiet and it was lonely. It was still. It was just my piano and myself. "I had a television and I would leave it on all the time just to feel like somebody was hanging out with me. And especially during the period when I was doing cocaine. It was like the drug was my friend. I never did it with other people. It's such a terrible way to fill that void, because it just adds to that void, because it's not real."