How does feminism play an important role in the main character of Medea?

I can't think of a woman in literature who takes more control of
her situation than Medea.  She does what she thinks she needs to do no matter how horrrific the
consequences.  Before the play opens, the tale of Medea includes her helping Jason win the Golden
Fleece by the use of Medea's magical help.  In doing this, she wins Jason's heart, but she
betrays her father, the owner of the Fleece.  As Jason and Medea are fleeing her homeland, she
keeps her father from catching them my killing her own brother on board Jason's ship dismembering
his body, and then throwing the parts overboard one at a time so that her father would have to
stop and collect them for burial.  Talk about determination!

At the
start of play we learn that Jason has left Medea to marry this princess of Corinth.  Jason thinks
he is bettering his family's situation in Corinth, but Medea only sees it as the ultimate
betrayal and a selfish act.  She can't let the act go unpunished -- she is way to full of pride. 
Unfortunately for her, she also knows that no matter what she does to punish Jason will bring
retribution on her (and her children).  She hates Jason so much and values her personal sense of
honor so greatly that she does the unthinkable.  She kills Jason's new wife. That, all by itself,
shows a pretty strong feminist will -- she will not let her status as a woman be demeaned -- the
man, Jason, can't just do whatever he pleases.  The 2nd, even more horrific act, is that she then
kills her own children.  She justifies this act by explaining that it would be better for them to
die at her hand as opposed to King Creon's men who are now her bitter enemies.  It takes an
incredible amount of strength to go through with the act of murder of her own children.  This is
also used as the ultimate punishment for Jason -- he lives on to mourn all he has lost, knowing
that his actions made Medea take her actions.

While Medea's choices
are abhorent, there is a strong streak of feminism in them.  She refuses to just stand by and let
the men in her life (father and Jason) determine her outcome.  She takes control of her
destiny.