I remember reading a story about someone who killed their parents because they thought their parents was their lover with someone else. The parents visited them and slept in their bed. But they didn't know that their parents came. They only realized after they killed their parents. I think it was Greek mythology.
Anyone knows who is it about?
This is the legend attached to Julian the Hospitaller, who may, himself, be legendary. It is not Greek myth.
The Golden Legend recounts that witches cursed him to kill his parents at his birth, and his father heard them. His mother prevented the father from killing him, but when he heard the story, he left to prevent it. He married, his wife offered a traveling couple hospitality and her own bed for the night, and he returned, found them in it, and killed them.
There is also the tale of Clytemnestra (sister of Helen of Sparta/Troy), and her adulterous lover Aegisthus by Orestes with the help of his sister Electra.
