LONDON — American pop sweetheart Katy Perry is revealing a vulnerable side as she attends the European premiere of her new film. “Part Of Me” premieres in London on Tuesday. It's a 3-D behind-the-scenes look at the ups and downs of the 27-year-old singer's life over the past year. Having spent most of it doing a world tour, fans are treated to performances, backstage antics and the occasional breakdown. Perry also lets the cameras follow her through the breakup of her marriage to British comedian Russell Brand. Directed by Dan Cutforth and Jane Lipsitz, “Part Of Me” hits U.K. theaters on Thursday. — AP