Oedipus

The catharsis is ultimately reached when he he stabs himself in his eyes to blind himself on page 61. This is the catharsis because it is the emotional cleansing in the audience. 

I think Oedipus is culpable for his actions because he was the one who made his choice to leave Corinth, and go to Thebes because he heard what the prophesy was, and he was afraid he was going to kill his father, and when he left his home he meet the king and killed him without knowing it was his father.