What effect does Hester's information about Chillingworth have on Dimmesdale and how does his reaction change?Nathaniel Hawthorne's "The Scarlet...

In the "intense seculsion" of the forest, Hester awaits the passage of the Reverend Dimmesdale in Chapter XVII of "The Scarlet Letter."  As she calls to him, the minister wonders if he has heard a voice, or if it is "a spectre that had stolen out from among his thoughts."  But, he does recognize Hester and they walk together:

Thus they went onward, not boldly, but step by step, into the themes that were brooding deepest in their hearts.

Of course, the "theme brooding" in the heart of Hester is her guilt and anguish at not having revealed to her lover that Roger Chillingworth is, in reality, her husband.  When the minister confesses to her that his life is all "falsehood," and he wishes that he could have just one friend to whom he can be honest about her sin, Hester feels that she must "interpose" and be honest herself since she realizes the effects that Chillingworth's presence is having upon Dimmesdale.

The minister looked at her, for an instant, with all that violence of passion, which--intermixed, in more shapes than one, with his higher, purer, softer qualities--was, in fact, the portion of him which the Devil claimed....Never was there a blacker or a fiercer frown than Hester now encountered.  For the brief space that it lasted, it was a dark transfiguration.

The exertion of such emotion, throws Dimmesdale to the ground.  He exclaims, "I might have known it!....Why did I not understand it?"  In addition, he feels shame that the cuckolded husband should be privy to his soul.  Blaming Hester for such exposure he tells her, "Woman, woman, thou art accountable for this!  I cannot forgive thee!"

But, his beloved Hester begs him to forgive her, and he acquiesces:

'I do forgive you, Hester....We are, not, Hester, the worst sinners in the world.  There is one worse than even the polluted priest!  Taht old man's revenge has been blacker than my sin.  He has violate, in cold blood, the sanctity of a human heart.  Thou and I, Hester, never did so!...What we did had a consecration of its own.

This meeting of Dimmesdale and Hester and his words are pivotal to the theme of the hypocrisy of Puritanism in its excessive punishment for overt sin while secret sins of the vilest character go unpunished.