Complex sentence: Seeing the disturbing appearance of her baby's eyes and demanding to know what had caused the deformity, Rosemary is then told that Guy is not the baby's father and that the baby, named Adrian, is actually the spawn of Satan.
Split into simpler sentences: Seeing the disturbing appearance of her baby's eyes and demanding to know what had caused the deformity, Rosemary is then told that Guy is not the baby's father. The revelation that the baby, named Adrian, is actually the spawn of Satan.