regrettingly
regretfully
fear
guilt
ruesome
pity
regretlessness
shame
too bad
remorse
regrettable
compunction
self-reproach
live to regret
regretter
regretfulness
lamentably
ochanee
lament
bewail
bemoan
deplore
whip the cat
regretful
regrettableness
regret
repine
afraid
sayang
eat one's words
apology
apologize
remorsefully
contritely
ruefully
wear sackcloth and ashes
Ichabod
prick
seem like a good idea at the time
desire
repent
semiapologetic
whoops-a-daisy
whoopsie-daisy
lamenting
repentance
rue the day
sorriness
sorrily
resentable
regrettably
tristfully
pang of conscience
sorry
soz
if only
regretting
unhappily
ill-placed
complainingly
afterthink
remorseful
apologetic
poop
waste
mean
pityingly
lamentingly
disappointedly
fuckity bye
ruthfully
attrite
ashamed
outgave
belatedly
disbecame
revulsed
aiyo
forgave and forgot
alack and alas
bummer
pratfall
libellously
look back
poor
guilt pang
no such luck
sadly
F
repathologize
half-past-six
guilty
could have, would have, should have
thinko