compunction, remorse, self-reproach - a feeling of deep regret (usually for some misdeed)

survivor guilt - a deep feeling of guilt often experienced by those who have survived some catastrophe that took the lives of many others; derives in part from a feeling that they did not do enough to save the others who perished and in part from feelings of being unworthy relative to those who died; "survivor guilt was first noted in those who survived the Holocaust"