A blanket is supposed to be comfort: something warm you pull around yourself when the world feels cold. Here, the speaker does that, but what they wrap themselves in is "hateful words" and "terrible thoughts." The poem's quiet shock comes from how ordinary the action sounds. There's no outcry, just a plain statement of what happened.
The last line is the heart of it. The speaker "called it 'home,'" and the quotation marks suggest doubt. Maybe they know it isn't really home, but it's the only shelter they have. The poem seems to describe someone who has grown so used to harsh voices, perhaps their own inner critic or things said to them by others, that the cruelty has started to feel familiar and even safe. The poem doesn't say which.
The mood is bleak but calm, almost resigned. The short lines and flat tone make the speaker sound tired, as though they've stopped expecting anything gentler. It's a small poem that leaves an uneasy question behind: what do we mistake for comfort just because it's what we know?