Fame didn’t erase the damage. Alcohol, depression, shattered marriages, and staggering betrayal nearly finished what his childhood began. Yet each time, he crawled back to the keys. Now, with a fragile brain and a body in rehab instead of on tour, Billy Joel is once again fighting time, pain, and fear. His daughter calls him a trooper. Fans call him a legend. But at his core, he’s still that kid at the piano, refusing to let the darkness have the last note