Anxiety is the subject here, and the speaker describes it as something that creeps in and takes over the body. It begins as a "numbing feeling" in the mind, then spreads "like a virus" until it reaches the heart. From there the images turn to water: drowning, choking on tears, a "tsunami" in the soul. The speaker says the pain is not only mental. It becomes physical, with a grabbed chest and gasping for air.
What hurts most is the loneliness. The speaker longs for an anchor, someone who will whisper that everything will be okay, but "no one comes." Even worse is the fear that no one will understand, and that fear feeds the panic further. By the end the speaker breaks down and apologizes over and over, to "nothing," "no one," "everyone," "everything." The mood is raw, desperate, and heavy. The short lines and repetition make the poem feel breathless, like the panic it describes.