At just 17 years old, Pattie Mallette got pregnant by her on-off boyfriend, Jeremy Bieber, and found herself facing a very difficult decision. “People close to me were pressuring me not to keep the baby,” Pattie tells In Touch in an exclusive interview. “But I couldn’t do it. I decided, whatever it took, I had to keep him.” Suddenly faced with the harsh reality of being a single teen mom, Pattie gave up partying and held down three jobs in order to support her beloved baby boy — and never imagined he would grow up to be music sensation (and millionaire) Justin Bieber.Though money was tight when Justin was a child, Pattie has never once regretted her decision to keep her son, who remains her biggest cheerleader and best friend. “Watching him every day, I’m so inspired,” says Pattie, who details her hardscrabble life and her son's incredible rise to fame in her memoir, Nowhere But Up. “I’m in awe.”For more of Pattie's exclusive interview — including secrets of Justin's childhood and love life — pick up a copy of In Touch, on newsstands now.