Be real aggressive in dealing with this. You can break them of this habit and really need to. I do not mean be unkind to this hen - just stay on top of the situation as best you can and try different things until you've run out of ideas. She will decide to stop breaking eggs soon or she needs to go.
You have already gotten a couple of good suggestions.
Be sure that the eggs have good hard shells so that they aren't breaking by accident. Any broken egg will be eaten - even by hens that would never break an egg deliberately. Feed oyster shells.
Be sure that the protein level of their diet is high. I have fed rinsed, canned tuna when I was confronted with this problem.
Be sure that the nest boxes are very, very comfortable. Now is not the time to tolerate dirty boxes or inadequate nesting material. The nests should be somewhere quiet. Some folks report very good results with darkened, curtained nestboxes. If they can't see the eggs, they apparently can't eat them but they will lay eggs in the dark.
I got a hen past this problem. Here is wishing you the very best of luck.
Steve