Perez Hilton has alleged that Lady Gaga “used him as a tool” to write “terrible” things about her pop star rivals, including Christina Aguilera.The notorious blogger, whose self-named site was the lynchpin of the celebrity gossip industry throughout the 2000s, has claimed that his one-time friendship with the star led to “things I’m most ashamed of”.In Hilton’s new memoir, TMI: My Life in Scandal, he claims that he “deliberately hurt” Aguilera after he and Gaga speculated that she had “copied