Why does story upset Oedipus in

The story upsets Oedipus because it reveals the truth about his past and his relationship with his parents. He learns that he unknowingly killed his father and married his mother, fulfilling the prophecy that was foretold at his birth. This revelation causes immense emotional distress and turmoil for Oedipus, leading him to gouge out his eyes in despair and self-punishment.