Complex sentence: To atone for this transgression, Giasone agrees to have Besso murder Isifile in an aside to Medea, who then leaves, pretending to allow Giasone to return to Isifile.
Split into simpler sentences: To atone for this transgression, Giasone agrees to have Besso murder Isifile in an aside to Medea. She then leaves, pretending to allow Giasone to return to Isifile.