What is the peripetia in Oedipus Rex

Peripeteia is the sudden change in a situation. This is a term used to describe plot twists in literary works, like the Greek play Oedipus Rex by Sophocles. The peripeteia is the climax of the plot of a piece of literature.

when he marries his mom, just what his mom thought was not going to happen when she sent him away