Carly Simon shares rare insights into how her divorce from James Taylor impacted their two kids — Sally and Ben — in an emotional new song, Page Six can exclusively reveal. “Comes in Waves” — Simon’s upcoming album set to debut this Friday — features “Mother of Pearl” as its fifth track. “I can see you at 7, a child of divorce,” she sings. “How can it be that we gave you no choice? / It was your job and Ben’s to drown out all the noise.” The proud mom goes on to recognize her daughter’s strength at such a young age. “But my girl, oh my girl. / Even then you were shining, you were my mother of pearl,” she sings. The song begins with Simon…