bitterly in WordNet English dictionary

1. extremely and sharply
   "it was bitterly cold"; "bitter cold"
   piercingly  bitterly  bitingly  bitter  piercingly  bitterly  bitingly  bitter 
   
2. with bitterness, in a resentful manner
   "she complained bitterly"
   bitterly  bitterly 
   
3. indicating something hard to accept
   "he was bitterly disappointed"
   bitterly  bitterly