Night is when the speaker finally drops the act. In the dark, with no one to hear, she describes cutting her skin, wiping away tears, and writing out her will. That last detail is the most alarming: it suggests she is thinking about dying, or at least feels that deeply hopeless. Even the writing is a kind of release, with tears staining the ink as she puts down what she feels.
The third stanza names the core of her pain: "Everyone's around me / But nobodies home." She isn't physically alone, but no one sees what is going on inside her, or perhaps no one is really present for her. The repeated opening line, "In the dark of the night," works like a drumbeat, pulling each stanza back to the same lonely hour. The short, plain lines make the mood quiet, heavy and raw. The ending, "I'm only one person / I'm only one girl," sounds small and tired, as if she is saying that it is all too much for one person to carry. If a poem like this feels close to home, it is worth telling someone you trust.