My Dirty Little Secret
Hester knows what's ailing Dimmesdale on page 151,"She had witnessed the intense misery beneath which the minister struggled, or, to speak more accurately, had ceased to struggle."
Standing with him on the scaffold, she realizes that the secret is tearing him apart from the inside out. Even knowing this, she does not know how to help him. Everything she can consider she has promised not to do. It will be interesting how she dealing with this upon further reading
It's interesting how this seems to be affecting the minister worse than Hester when he managed to escape the public eye in this matter. I guess this is Hawthorne's way of getting the idea across that it is not wise to bottle things up.
I think Hester was actually hurting the minister more by not saying who the father of her child is. He is being tormented by his own guilt and the fear that others will not only find out what he has done, but what he has concealed.
His guilt is tearing him apart.