What is the impact of Hester's decision to reveal Chillingworth's identity to Dimmesdale? It breaks Hester's heart because Dimmesdale refuses to forgive her for her deception

It changes the course of events for all the major characters from this point on.

It has little impact because Dimmesdale is too damaged to remove himself from Chillngworth's hold,

It finally brings joy to little Pearl because Dimmesdale agrees to acknowledge his daughter publicly.