Kept the Old Key Returned

After we split, I still had a key I'd promised to return. I kept it. Once, when I knew they were out, I let myself in just to grab my stuff. I stayed longer than I needed, looked around, checked the fridge, even sat down like I still belonged there. Nothing was taken, but something was crossed. I left everything as I found it and walked out feeling sick. The next day I returned the key with a smile, as if I'd done the right thing.