Letitia Elizabeth Landon wrote the poem "Revenge" in the early 1800s, but the theme is just as relevant today as it obviously was then. The speaker of the poem is a woman who has been scorned (dumped, put aside, left) by the man she loved, presumably because he loved another woman. In any case, he now loves someone else as he once loved her, and she tells him to go ahead and stare at her hair and smile as if he is drinking in the air her breath exhales. The ex-lover hopes he swears to this new woman that she is the only thing his heart worships. In short, she hopes he does everything possible to demonstrate his love for the other woman.
If he does these things, she is satisfied, because she has seen how the other woman scorns and ignores him, and this is the speaker's great revenge--that he will feel now what the speaker felt when he left her. She says:
'Tis well: I am revenged at last;
Mark you that scornful cheek,
The eye averted as you pass'd,
Spoke more than words could speak.
The speaker of the poem details the agony she has experienced since he left her, the "bitter tears" she has wasted on him,
The racking doubts, the burning fears,...
By the nights pass'd in sleepless care,
The days of endless woe.
Notice the imagery of torture the speaker uses to depict her pain, and she is glad that now her ex-lover, too, will experience this kind of pain:
All that you taught my heart to bear,
All that yourself will know.
In the true spirit of a scorned woman who wants to make sure that the one who left her for another woman is now feeling the same pain she experienced, the vengeful speaker wants him to experience even more pain than she did. She says she does not want him to die too soon ("laid within an early tomb") or she might forget too quickly how much he hurt her and weep for him because he is dead. Obviously she wants his pain to be as prolonged and as painful as possible; she believes what is happening to him now ("to live and love in vain") is "fitting punishment," and she tells her broken heart to be content to "feed upon his pain."
She tells him to go and spend his time watching the other woman's "lightest sigh," knowing that she is not interested in him and he will never have her. The speaker finishes the poem with some more specific punishment imagery:
'Tis well: the rack, the chain, the wheel,
Far better hadst thou proved;
Ev'n I could almost pity feel,
For thou art nor beloved.
Loving someone who does not love him in return is an even greater punishment than physical torture ("the rack, the chain, the wheel"), and the speaker almost feels sorry for him. Almost.