Complex sentence: Eurytus was aware that Heracles had killed his previous wife, Megara and their children and thus afraid that Heracles would very likely kill Iole and any grandsons she may have should Heracles get into a mad rage again.
Split into simpler sentences: Eurytus was aware that Heracles had killed his previous wife, Megara, and their children. He was afraid that Heracles would very likely kill Iole and any grandsons she may have should Heracles get into a mad rage again.