lament
deplore
bemoan
bewail
remorse
self-reproach
compunction
fear
regret
regrettable
too bad
regrettingly
regretlessness
live to regret
guilt
regretfully
shame
ruesome
rue the day
apology
wear sackcloth and ashes
regretful
could have, would have, should have
whip the cat
regrettableness
desire
obliviousness
oblivion
Ichabod
bitter
apologize
F
sayang
eat one's words
regretter
seem like a good idea at the time
pang of conscience
regretfulness
ochanee
pity
repine
lamentably
regretting
aiyo
shock
penitence
penance
alack and alas
resentable
repentance