The speaker feels trapped by their own voice. The opening image sets the tone: a rusting oven used for bread. An oven should nourish, but a rusty one spoils whatever goes into it. In the same way, the speaker's words seem to come out tainted, so that even a wish to speak kindly turns into something harsh.
The second stanza says this outright: "I cannot answer otherwise / than in abuse." There is no excuse offered, only a flat admission, and it sounds weary rather than proud. The last lines are the most painful. The speaker seems to betray "the very eyes" they are asking to "just be quiet," as if they want peace or forgiveness from someone, yet the way they ask only hurts that person further. The poem's mood is tense and regretful, with a bleak sense of self-awareness. The speaker sees the damage clearly and still can't stop it.