Where does victor say that he suffered the most?

There are several places in the text where Victor claims to feel extreme suffering, typically when someone he cares about has been murdered by his creation. For instance, when Justine awaits execution for the murder of Victor's brother, William, however, Victor seems to be in the most agony. As Justine and Elizabeth mourn Justine's fate together, Victor says,

The poor victim, who on the morrow was to pass the awful boundary between life and death, felt not, as I did, such deep and bitter agony.  I gnashed my teeth and ground them together, uttering a groan that came from my inmost soul.

In other words, despite the fact that Justine is about to be hanged for a crime she didn't commit—worse yet, she has to live with the fact that she's been convicted of having murdered one of the people who is the most important to her in the world, an innocent child that she would never dream of hurting ever—Victor claims that his pain is the worst. He feels much sorrier for himself and his pain than he does for Justine. He thinks that her knowledge of her own innocence, despite her conviction, must make it easier for her to face her fate than his guilt and his knowledge of the role he's played in this tragedy. Victor claims to feel the most agony here.