(a.) Full of regret; remorseful; sorrowful\.

apologetic ashamed baffled balked betrayed bilked blasted blighted chapfallen conscience-smitten conscience-stricken contrite crestfallen crossed crushed dashed defeated disappointed dished disillusioned dissatisfied foiled frustrated full of remorse guilty ill done-by ill-served let down mournful out of countenance penitent remorseful repentant repining rueful sad self-accusing self-condemning self-convicting self-debasing self-flagellating self-humiliating self-punishing self-reproaching shamefaced shamefast shameful sorely disappointed sorrowful sorry soured thwarted unhappy about wistful