/ ˈbɪtəli; NAmE -tərli/ adverb
1.
in a way that shows feelings of sadness or anger :
She wept bitterly.
They complained bitterly.
The development was bitterly opposed by the local community.
2.
( describing unpleasant or sad feelings ) extremely :
bitterly disappointed / ashamed
3.
bitterly cold very cold