A speaker stares at their own reflection and asks the same question again and again: what have I done? The poem never says what the act was. We only see its effects, which is what makes it unsettling. The speaker's eyes look "cold, dead, dark, somber," like those of a stranger, and the mark they made weighs "heavy" on their heart.
The feelings here are tangled and contradictory. The act has made the speaker "feel again" and "see again," even feel "so like me again," yet it is also "beautiful," "dangerous," and "toxic." The speaker seems to be caught between a strange relief and deep regret, and calls this "ironic." By the end they feel "beyond repair" and "just out of reach," as if cut off from themselves. The short, repeated lines create a haunted, numb, uneasy mood, and the final unanswered question leaves it hanging.