Barry Manilow has reflected on his “nightmare” lung cancer diagnosis, saying it led to an even greater appreciation for life. “They don’t even know how long I had this thing sitting on me. It could have been years,” the singer told People in an exclusive interview, published on Tuesday. “If it had gone any further, then I would be up shit’s creek. It just so happened that it hadn’t spread, and boy oh boy, I thought I might be dying.” The Copacabana hit-maker explained that his doctor ordered an MRI for him after he complained about hip pain in November. However, he also ordered an MRI for Barry’s lungs after learning the musician had recently faced two cases of bronchitis. That’s when he found something. “If he hadn’t done that, man … He saved my life, because there’s no symptoms for what I had. I could go on, nothing hurt — but they found the dot in my lung,” the songwriter said. “They called me and said, ‘Could be cancer.’ That’s a bad word. ‘Not …