How does Medusa play in the mythology?

Medusa was a young and beatiful woman; who was one of three sisters called the "Gorgons". Medusa had a thing for Poseidon, god of the sea, and so they had a sexual affair in Athena's temple: a highly disrespectful thing to do. In result, Athena turned Medusa into a terrible, green monster with hypnotizing powers with her eyes and the ability to turn anyone into stone with her eyes and hair: a headful of hissing and poisonous snakes. The other Gorgons have been taking revenge and Medusa has too, and Athena is still really pissed off with Poseidon.