Izzy's poem is a short, blunt outburst of hurt and frustration aimed at one person. The speaker begins small: even the "simplest things" this person does bring pain and confusion. That detail suggests the damage isn't from one big betrayal but from a steady wearing-down, day after day.
The speaker admits they often don't understand the world, but they understand this person even less. The short, repeated lines ("The way you talk / The way you act") sound like someone counting up complaints, unable to stop. The key turn comes with "It's not who you are / It's what you are." The speaker seems to say the cruelty is part of this person's nature, not just a bad mood. Yet the next line adds a sharper accusation: they could have been anything, and they chose this.
The mood is raw, bitter and bewildered. The final line, "My living nightmare," lands like a verdict, leaving no softness at the end.