The speaker describes a moment that keeps coming back: an encounter that makes them want to shout straight into someone's face. What stops them is the respect they were taught, which they hold onto as a kind of self-control. The third line is a little tangled in its wording, but the meaning seems clear enough: restraint is a struggle, not something that comes easily.
To settle down, the speaker tries to breathe, repeating "deep breath, deep deep breath" as if coaxing themselves through it. The repetition makes the effort feel real and a bit desperate. Then the mood shifts. Instead of relief, they feel "empty" and "sad," and the final line admits the rage hasn't gone anywhere. The poem's tone is tense and honest, and it leaves us with an uncomfortable idea: staying polite and calm on the outside doesn't mean the anger has stopped, and it can leave a person drained inside.