Oedipus's tragic flaw is his yearn for knowledge (sight). He seeks to learn who killed Laius, and who his real parents are, which leads to his catastrophe.
Oedipus is too proud of himself, and cannot fathom that the prophecy could be occurring under his nose. By trying to find out his "proud backstory", he only finds that he has completed the prophecy without realizing it.
Oedipus was a fair king loved by all with a happy family and wife until he is told to find who killed Laius to stop the rot in the city. He talks to the prophet and his life is turned on its head.
Oedipus realizes that staying blind to his past would have allowed him to see a better future, as he learns that Jocasta is his mother, and the old man he killed was Laius, his father and king of Thebes.
Oedipus rushes to his bedroom to find that Jocasta has hung herself, and purges his eyesight by jamming her brooches into his eyes. He goes blind, and is banished from Thebes to cure the rot.
The characters finally realize the prophecy has come true, and react to it. The audience has known that the prophecy has come true for a while, and now they feel suffering for Oedipus as he suffers greatly.