Two short lines carry a lot of hurt. The speaker describes a familiar, painful situation: you bend over backwards to make other people happy, and instead of thanks you get an insult. The word "disgusting" is harsh and personal. It doesn't criticize something you did; it attacks who you are.
The opening word, "sometimes," matters. It suggests this has happened more than once, but not always, which makes it feel like a pattern the speaker can't quite predict or escape. The shift from "you do everything" to "they just say" sets effort against dismissal. The word "just" makes the response sound flat and careless, as if all that work counted for nothing.
The mood is bitter and tired, with a quiet sense of being unappreciated and wounded. Speaking as "you" rather than "I" may be a way of holding the pain at a distance, or of saying that many people know this feeling. The poem's brevity makes the insult land bluntly, with no softening afterward.