what terrible plan does medea reveal to the chorus? why will she do it?

With her security certain, Medea tells the Chorus of her plans. She will kill Jason's new bride and father-in-law by the aid of poisoned gifts. To make her revenge complete, she will kill her children to wound Jason and to protect them from counter-revenge by Creon's allies and friends. Many scholars now believe that the murder of Medea's children was Euripides' addition to the myth; in older versions, the children were killed by Creon's friends in revenge for the death of the king and princess. The Chorus begs Medea to reconsider these plans, but Medea insists that her revenge must be complete.