What conclusion regarding Dimmesdale does Chillingworth reach?

Chillingworth realizes that Dimmesdale is hiding some dark secret. He therefore expends a great deal of time and energy to make Dimmesdale reveal what is troubling him. Dimmesdale fails to realize that Chillingworth is in fact his enemy. He is so terrified of everyone in the town finding out his secret that he is blind to any enemy within his own home.