Who is to blame in Medea?

I think Meda really lacked control of her passions and rage. Medea is a woman of extreme behavior and extreme emotion. For her passionate love for Jason, she sacrificed all, committing unspeakable acts on his behalf. But his betrayal of her has transformed passion into rage. Her violent and intemperate heart, formerly devoted to Jason, now is set on his destruction. The Greeks were very interested in the extremes of emotion and the consequences of leaving emotion unchecked; they also tended to see strong passion and rage as part and parcel of greatness. Medea is an example of passion carried too far, in a woman perversely set on choosing rage over mercy and reason.