The speaker describes a second self living inside them, one they see as an enemy. Her "brittle bones" and "poisonous envy" make her seem both fragile and bitter, a presence that is weak and dangerous at once. Calling her "the ultimate freak show" shows how ashamed and disgusted the speaker feels, as if this hidden part of themselves is something to be stared at and hidden away.
The feeling shifts as the poem goes on. At first the speaker is angry and rejecting, longing for the day "she goes away." Then comes a hesitation: "But I fear / I fear." The broken, repeated line makes the speaker sound stuck, unable to finish the thought. When it arrives, the fear is plain and heavy: she "will always be here." The mood is tense and uneasy, ending in quiet dread. The short lines and spare wording make the confession feel raw, as though the speaker is admitting something they can barely say aloud.