Agatha Christie said this quote

Mademoiselle, I speak as a friend. Bury your dead! ... Give up the past! Turn to the future! What is done is done. Bitterness will not undo it.''I'm sure that would suit dear Linnet admirably.'Poirot made a gesture. 'I am not thinking of her at this moment! I am thinking of you. You have suffered - yes - but what you are doing now will only prolong the suffering.