Is she stepping on the eggs and breaking them or is she pecking at them purposefully to open them up? The latter is much more concerning as egg eating is difficult (to say the least) to break *and* can spread through a flock as other birds see the first bird engage in the behavior.
Laying in the same nest is typical chicken behavior and as long as the nest is sufficient in size and bedding is not going to cause egg breakage *if* the eggs are appropriately shelled (weak, thin shelled eggs are more at risk for breakage). It is instinctual for them to use a nest that already has eggs in it vs. seeking out an empty nest "of their own".
One option that you might consider, especially if the bird is intentionally cracking eggs open, is to install roll-away nest boxes which move the eggs out of reach when they are deposited. Alternatively, removing the egg eater from the flock is another sure solution.