grammaticality - Woe is me - what does it mean?

What exactly does the phrase 'Woe is me' mean? A google search returns many results ranging from FML to just having a bad day. There are many references to the phrase being grammatically incorrect and thus meaning nothing, but it seems like it is in use. So, is the phrase acceptable in common English despite being grammatically incorrect? Or is it, infact, grammatically correct?

Edit: What I was able to find using Google:

1. Phrases.org.uk: "I am distressed; sad; grieved."


2. onlinecollege: "Woe is me: It sounds a bit like Yoda-ese, but instead of saying FML, go biblical with "woe is me."


3. UrbanDictionary: "Both answers that tried to explain are incorrect in explaining the grammaticality of the phrase. The verb "to be" is an intransitive verb, meaning it cannot take an object." (Refer to the link for complete text)