Question about Macbeth?

Lady Macbeth is asking Macbeth why he is isolating himself from the world. He is making his "bad thoughts" his "companions," meaning that's all hes thinking about. She said he should stop thinking about what happened because he can't change it, there's no "remedy" and "what's done is done." He's driving himself mad by only allowing himself to think about what bad thing happened in the past.