Hester and Dimmesdale meet in the forest and hold hands. Dimmesdale says life with a scarlet letter would be preferable to his life of deception, since Hester is the only person with whom he can be himself. The rest is emptiness, falsehood, and death.
Dimmesdale knows that his secret sin and the split identity it creates in him is actually killing him.
Hester reveals to Dimmesdale that Chillingworth was her husband. Dimmesdale, furious, blames her for his suffering. But he then forgives her and says Chillingworth's sin was far worse than theirs.
Hester and Dimmesdale kept secrets to protect themselves. Chillingworth kept secrets in order to harm others.
Dimmesdale says living under Chillingworth's control is worse than death, but he sees no way out. Hester tells him to consider a life beyond Boston, in the safety and anonymity of Europe. Dimmesdale says he lacks the strength and courage to venture out alone. Hester says he wouldn't have to go alone.
Hester gives Dimmesdale a solution to save himself that isn't confession: leave Boston and the Puritans with her. But note that this solution involves running from secrets, not confessing them.