Betrayal is never defined here. Instead, the speaker describes how it hits the senses: it tastes like copper, looks like a dark cavern, sounds like chaos. Each time, the speaker reacts with a strange, almost clinical act. They bite their lip to check their blood type, close their eyes to compare shades of black, stay silent to notice how quiet things could be. The flat little refrain "Of course" sounds like a shrug, as if the speaker is numb, or trying to be.
That detachment feels like a way of coping. Turning pain into small experiments keeps the speaker at arm's length from it. But the last stanza breaks the pattern. All three sensations arrive at once, and the repeated "scream and I scream and I scream" shows control slipping. Even then, the speaker only wants to hear their own voice, which suggests loneliness and a need to prove they still exist. The mood is bleak, dazed, and quietly desperate.