Hard to say but since the roots were unaffected, there is a good chance it will recover, albeit not quickly. This would be the same thing as if the shrub had been hit by a late frost that killed the leaves or even the stems... in several weeks or a month or so, the shrub would generate new growth from stems and or from the base. As far as whether your husband can come back close to the hydrangea, hmmm, maybe not? Hee hee hee! ;o)
I would also not go heavy on fertilizing but adding some alfalfa or alfalfa meal might be nice. Alfalfa is often synonymous with the plant growth hormone tricontanol, considered the most or one of the most powerful plant growth promoter, and alfalfa contains copious amounts. So using it might help speed the recovery.