Just minutes before she was set to take the stage last night at Purdue University, Lady Gaga found herself struggling to breathe. The "Paparazzi" singer reluctantly canceled her show and took to Twitter to apologize to her fans. "I've been crying for hours, I feel like I let my fans down 2nite. An hour before the show, I was feeling dizzy and having trouble breathing," she writes, adding: "Paramedics came to take care of me, and told me my heart rate was irregular — a result of exhaustion and dehydration. I can't apologize enough for how sorry I am. I could hear my fans cheering from my dressing room, I begged everyone to let me go on-stage. I am so devastated. I have performed with the flu, a cold, strep throat, I would never cancel a show just based on discomfort. I hope you can forgive me. I love my little monsters more than anything, you are everything to me."