What image closes “Remembrance”? How does this image create irony?

Emily Bronte's poem "Remembrance" features a speaker who reflects on a lost loved one, who has apparently been dead for fifteen years. The speaker laments the loss and discusses how she learned to live without the beloved. At the same time, she admits has felt no joy since the beloved's death. The speaker writes,

No later light has lightened up my heaven,
No second morn has ever shone for me;
All my life's bliss from thy dear life was given,
All my life's bliss is in the grave with thee. (Lines 17-20)

The speaker is openly stating that she will never feel "bliss" again; her chance to experience this feeling died with the beloved ("is in the grave with thee"). The metaphorical "later light" and "second morn" represent another beloved who might supplant the dead beloved in the speaker's heart. This stanza clearly repeats the idea that no new love has come, and no new opportunity for joy will ever present itself to this speaker.
The final three stanzas see the speaker wavering between emotions. In the sixth stanza, she says she learned to live without the speaker, though that life is "fed without the aid of joy" (24). In the seventh stanza, the speaker admits that she wanted to die, to "hasten / Down to that tomb already more than mine" (27-28). She once saw no point to living without her beloved. In this stanza, though, the speaker emphasizes how difficult it was to "wean" herself from the temptation to die along with the beloved.
In the eighth and last stanza, the speaker closes the poem by writing,



And, even yet, I dare not let it languish,
Dare not indulge in memory's rapturous pain;
Once drinking deep of that divinest anguish,
How could I seek the empty world again? (29-32)



Despite all of her best efforts, the speaker still must be vigilant, as she "Dare not indulge in memory's rapturous pain." This oxymoronic line suggests that a "remembrance" of the beloved is both pleasurable and painful: the love they shared clearly brings up strong emotions, but it can never be separated from the fact that the beloved is now dead and beyond her grasp. It is ironic that she can not even think of her beloved with pleasure or joy and that she even sees the remembrance of the beloved as somehow "rapturous." It is obviously dangerous for the speaker to "languish" in the memories of the beloved. She asks how she could ever "seek the empty world again" if she were to fully immerse herself in "that divinest anguish." The irony in the poem's final image is seen in the oxymoronic phrases "rapturous pain" and "divinest anguish." There is both the temptation and the danger in remembering.