The speaker wishes they were a gentler, sweeter person, with a heart full of "milk and cookies," but instead finds it churning with envy. The poem is about the shame of feeling jealous and the helplessness of not being able to switch that feeling off. In the first stanza, envy becomes a flooded space where the speaker gropes in the dark for a "golden drain plug" that would let it all empty out, but never finds it. They are left to drown alone.
In the second stanza, the image shifts to bees. Noise fills the speaker's head, and they become both hive and carrier, storing up a sugary nectar that their own feelings feed on. The sweetness is sickly, even "diabetic," suggesting that envy can start as something tempting and then poison you. The final image of the green apple of Eden suggests temptation and the fall, so giving in to envy feels like simply being human. The mood is heavy, anxious, and quietly self-critical, though also honest.