Complex sentence: She had given birth to their daughter and not long after, she left Knemon because of how poorly he treated her and went to live with her son, Gorgias, leaving Knemon with their daughter and Simiche.
Split into simpler sentences: She had given birth to their daughter and not long after, she left Knemon because he treated her poorly. She went to live with her son, Gorgias, leaving Knemon with their daughter and Simiche.