Great concept.
I'm not sure you need the part about preparing for the wedding in the logline, I would concentrate on the second sentence, it seems to have almost everything you need for your logline.
Here's your second sentence: "To prevent villagers from eating each other (literally) she must confront the witch and learn the truth about the village past."
You could then change it a little bit:
"When the villagers of her sleepy hamlet are turned into cannibals by an evil Witch, a naive girl must confront her town's dark past in order to lift the curse and save both her family and betrothed."
That example is still clunky-- (by clunky I mean the part in my example where I say "Confront her towns dark past," but is seems from your logline the villagers may have wronged the Witch in the past and the curse is her revenge)-- but hopefully you see where I am going with it.
Sounds like a great idea. With a little bit of re-arranging your logline will be much improved.
Good luck!