The speaker is stuck in the past, caught between two moments that sit side by side in memory. One is tender: dancing with a woman and hearing her sweet voice. The other is horrifying: her screams and the sound of her bones breaking. The poem never says exactly what happened, but the repeated phrase "I'm still a breath away" suggests that neither moment has really ended for the speaker. They feel close enough to touch.
In the last stanza, the speaker works out a private bit of logic. Hearts don't "break," because they aren't bones. They're muscles, so they rupture and tear. The comparison quietly echoes the sound of her breaking bones, as if the speaker's own pain is tangled up with hers. The line "no one can heal a ruptured heart" ends the poem on grief and hopelessness. The mood is quiet, raw and haunted, and the plain, flat language makes it hit harder.