The tone of this poem is certainly one of bitterness. She is bitter because they chose to label her a witch for no reason other than she lived a solitary, shabby life. She was bitter that God allowed her to be so treated. Bitter even against the women she helped, for they stood and watched her hang without trying to save her for fear they, too, would be labelled by association with her. She is bitter that the townspeople never tried to help her survive in her solitary, hard life. Her bitterness continues when she is cut down and found alive, for before he was labelled a witch; now people treat her as if she is one. Lastly, she is bitter that she did not die and must some time suffer a second death. Her second life, she is doomed to be a mentally deranged woman that everyone avoids.
The tone of this poem isn't really bitter, perhaps a more apt word would be sardonic. Mary is aware that as a woman she is vulnerable to the fates, hence her reference to free-will and the concept that "rumour" is on the wind hunting for a "neck" on which to land. She is disappointed in the "bonnets" that come to stare at her own mis-fortune, but realizes that they too are in danger. She wants and needs their "hands. . .words. . .shawls", but knows that they can't share them without endangering themselves. It isn't until the wee hours that she surrenders to panic. This is a wonderful poem.