Complex sentence: She was present, as was John Lennon's girlfriend Yoko Ono when the "White Album" was being recorded when she says she "was almost always stoned", and that: "the four began to diverge as artists during these sessions".
Split into simpler sentences: She was present, as was John Lennon's girlfriend Yoko Ono, when the "White Album" was being recorded. She said, at this time, she "was almost always stoned" and "the four began to diverge as artists during these sessions".