remorse
/ri-ˈmȯrs/
noun
a gnawing distress arising from a sense of guilt for past wrongs : self-reproach
compassion
penitence repentance contrition compunction remorse mean regret for sin or wrongdoing. penitence implies sad and humble realization of and regret for one's misdeeds. repentance adds the implication of a resolve to change.
idiom
feelings of guilt, remorse, or regret
He suffered no agonies of guilt/remorse/regret over his decision.