Why did Athena curse Medusa?

Medusa was the high priestess of Athena. She was beautiful and was desired by many men. One day Poseidon, god of the sea and earthquakes, took Medusa into Athena's temple and raped her. Athena was furious for being a priest of Athena you had to keep your maidenhood like the goddess. So to make sure this didn't happen again, Athena turned Medusa into a gorgon with snakes for hair and eyes that turn people to stone.