India, July 20 -- M usician Billy Joel has opened up in a new documentary called Billy Joel: And So It Goes about a painful time in his life. When he was just starting his music career, he fell in love with the wife of his best friend and bandmate Jon Small. At the time, Billy was living with Jon, Jon's wife Elizabeth Weber, and their son. Billy and Jon were in a band together called Attila. "I was in love with her, and I got punched in the nose for it, which I deserved," Billy says in the film, adding, "I felt really guilty. They had a child, and I felt like I ruined their family." After the affair, Elizabeth eventually left Jon Small and married Billy Joel in 1973. She also became his manager and played a major role in his early career success. However, their marriage ended in divorce in 1982 and was reportedly tumultuous, especially on the financial front. HTC...