Verses with the word bitterly in the Old Testament (7 verses):

Judges 5:23
Curse ye Meroz, said the angel of the LORD, curse ye bitterly the inhabitants thereof; because they came not to the help of the LORD, to the help of the LORD against the mighty.

Ruth 1:20
And she said unto them, Call me not Naomi, call me Mara: for the Almighty hath dealt very bitterly with me.

Isaiah 22:4
Therefore said I, Look away from me; I will weep bitterly, labour not to comfort me, because of the spoiling of the daughter of my people.

Isaiah 33:7
Behold, their valiant ones shall cry without: the ambassadors of peace shall weep bitterly.

Ezekiel 27:30
And shall cause their voice to be heard against thee, and shall cry bitterly, and shall cast up dust upon their heads, they shall wallow themselves in the ashes:

Hosea 12:14
Ephraim provoked him to anger most bitterly: therefore shall he leave his blood upon him, and his reproach shall his LORD return unto him.

Zephaniah 1:14
The great day of the LORD is near, it is near, and hasteth greatly, even the voice of the day of the LORD: the mighty man shall cry there bitterly.