I feel stupid

I was supposed to log some medicine in before I left work.  I hadn’t done it, because I thought someone else was doing it. I called work back, and my mood instantly down-spiraled when I was on the phone with my boss who clearly sounds disappointed. She said I’d have to talk to my direct supervisor about it tomorrow, who had to stay to finish it. Obviously I screwed up on this one. Granted I don’t think this is the end-of-the-world mistake, but I still feel stupid. I try and convince myself all the time that I am not stupid, and I just keep coming up with reasons for why I am stupid.  I try to convince myself with silly words of affirmation, and don’t get upset about this… but I am upset. I feel so useless.