Elizabeth is a good woman, confident in herself, aware of her own faults and yet moral in her own right.
She understands that John has cheated on her, but she confesses to having led him astray by keeping a cold house or cold presence in her relationship to him. She deprived him of intimacy.
By the end of the book, she sees that John has indeed "got his goodness now" as he feels like by not lying about being involved in witchcraft he is doing right by his God. If he is to be hanged, he feels it justified maybe on another level as he knows he deserves punishment for the sin of adultery.
Her knowledge of her driving him to cheat is a great example of insight into herself.