woe 
(wō)
(wō)n.
1. Sorrow or grief; misery. See Synonyms at regret.
2.
a. Misfortune or wretchedness: listened to his tale of woe.
b. A cause of sorrow or misery; a misfortune: economic and political woes.
interj.
Idioms: Used to express sorrow or dismay.
woe betide (someone)
1. Used to express the wish for someone to experience misfortune.
2. Used as a warning or allusion to negative consequences: "Even though my dad was no farmer, he was a crack shot and a very good hunter&.... woe betide the unwary moose that wandered down from Canada" (Howard Frank Mosher).
woe is me
Used to lament one's situation or fate.
woe to (someone)
1. Used to express the wish for someone to experience misfortune.
2. Used as a warning or allusion to negative consequences: "Our sun will be a red giant, and woe to any earthlings who may be around to witness its bloated blush, for the planet on which they stand will likely be vaporized in the expansion" (Natalie Angier).
[Middle English wa, wo, from Old English wā, woe!]