What is Dimmesdale's decision in response to Hester's plea that he leave the colony in Hawthorne's The Scarlet Letter?

In Chapter XVII of Hawthorne's The Scarlet Letter, Hester awaits the passage of Arthur Dimmesdale on a path through the forest.  When she encouters the minister, Hester, distraught over the tremendous psychological damage that Roger Chillingworth has wrought upon him, informs Dimmesdale of Chillingworth's true identity.  This new information greatly disturbs the minister, who does not at first forgive Hester.  But, strong of will, Hester insists that he forgive her.  Then, as a way out of his dilemma of living with his enemy--"Thou must dwell no longer with this man"--and in the community of "iron men" who will accept no penitenence for his sin, Hester suggests that Dimmesdale go farther into the forest and live in an Indian village, if need be to get away.  Dimmesdale rejects Hester's idea; however, undeterred, she demands that he act, "Then there is the broad pathway of the sea," suggesting that Dimmesdale return to London or other parts of the Old World.

Still, Dimmesdale refuses,

"It cannot be....I am powerless to go.  Wretched and sinful as I am, I have had no other thought than to drag on my existence in the sphere where Providence has placed me.  Lost as my own soul is, I would still do what I may for other human souls!  I dare not quit my post, though an unfaithful sentinel, whose sure reward is death and dishonour, when his dreary watch shall come to an end!"

"Fervently resolved," Hester will not accept her beloved minister's despairing response, insisting,

"But thou shalt leave it behind!....Begin all anew!....The future is yet full of trial and success.  There is happiness to be enjoyed!  There is good to be done!  Exchange this false life for a true one....Do anything save to lie down and die..."

In the "last expression of the depondency of a broken spirit," Dimmesdale tells Hester he must die in America; he declares,

'There is not the strength or courage left me to venture into the wide, strange, difficult world alone!' 

 To his words, Hester pours her strength of spirit, telling him, "Thou shalt not go alone!"  The chapter ends with the narrator's summation:  "Then all was spoken!"

With the fierce love and strength of Hester Prynne, Arthur Dimmesdale begins to believe that he can escape his Puritan fate, the "design" of his life can be changed despite the teachings of his faith.  For, there is a power in the human heart to repent and make amends for its sins.  One should not be condemned for a lifetime for a single sin.  Hawthorne's implication in this chapter of the redemptive power of good acts through the words of Hester is, clearly, counter to the ideology of his ancestors' Puritanism.