All went well for many years until a plague struck Thebes. So Oedipus sent Jocasta's brother Creole to the oracle. And the Oracle told Creole that the King Laios' murderer needs to be punished!
Kill the Old King's murderer!
Oedipus vowed to punish this murderer, but eventually found out that the man who he killed so many years ago was actually King Laios! He had murdered his father, and married his mother. Not epic. After figuring this out, Jocasta killed herself and Oedipus felt really, really bad.
Soon after, Creole became the acting ruler of Thebes and exiled Oedipus. After being exiled, Oedipus wandered the countryside as a beggar until he died.
Some time later Antigone, Oedipus' eldest daughter, returned to Thebes to find her two brothers, Eteocles and Polyneices fighting over who should rule the kingdom, as they originally agreed to take turns, but Eteocles said no and took the throne for himself.
After a long and bloody war, the brothers had both killed eachother, and Creon returned to take his rightful place at the throne. For Polyneices, he gave him a rightful anime burial, but left Eteocles unburied as punishment for his crimes.
Leaving Eteocles' body unburied angered Antigone, and she told him off for it, saying that they must obey the God's will no matter the consequences. But Creon didn't care for he was king and because he was king, he could do whatever he pleases.