Mary Helen Bowers, the professional ballerina who began training Natalie Portman in 2008 for what some are calling the role of her life, credits the details of “Black Swan” — big and small — for making it as true as possible to the life of a soloist in the competitive New York City ballet world.From the focus of ripping apart brand new pointe shoes — “which I know sounds crazy,” Bowers says — to the rigorous practice schedules, she felt her own life was constantly on camera. “I love the scene where Natalie’s character calls her mom from the bathroom to tell her that she got the part in ‘Swan Lake,’ ” Bowers says. “The day that I was asked to join NYCB, I did the same thing. As soon they gave me the news at the school (of American Ballet), I ran straight upstairs, pulled the phone into the bathroom … and called my dad. “I burst into tears as soon as he picked up, and of course he thought something was really wrong. I was just so overwhelmed with emotion. I was excited but also really shocked,” recalls the prima ballerina, who retired at 25 to pursue a college degree at Columbia U. Unlike Portman, who danced until 12, Bowers had to make a tough decision, as a child, to continue her life in ballet. “It definitely wasn’t cool in junior high when everyone else is trying out for cheerleading, to have a life consumed by ballet,” she says. This decision, however, would prove lucrative to the youthful Bowers, who left home at 15 to attend the New York City Professional School and study dance at the School of American Ballet. She was hired just one year later as a company member of the New York City Ballet and began an illustrious, and now famous, career.