Jocasta walks in on Creon and Oedipus arguing and tells them to cut it out.
Jocasta assures Oedipus that prophecies are consistently false and cites the example that her first husband, Laius, was prophesized to be killed by his own son, but that his son was killed as a baby.
Oedipus and Jocasta are somewhat relieved to find out from a messenger that Oedipus’s father has just died of natural causes, which means Oedipus couldn’t have killed him.
Oedipus, however, is still worried about the sleeping with his mother part of the prophecy. Jocasta tells Oedipus he’s better off not thinking and worrying about it.
The messenger informs Oedipus and Jocasta that the King of Corinth and his wife were not Oedipus’s real parents. Oedipus was discovered with his feet pierced and tied by a shepherd who then gave him to the messenger.
Although she has no lines here, Jocasta presumably gets really nervous at this part.
Oedipus learns that the shepherd who originally found him is still living. He summons him. Realizing that she is Oedipus’s mother as well as lover, Jocasta suggests that Oedipus drop the issue before he discovers more than he bargained for.
Jocasta makes reference to seeing Oedipus for the last time and runs off in total grief. Oedipus assumes she’s ashamed of his low birth and vows to set things right.