Problems with my memory at school

This morning when I went into a second-grade classroom, the teacher called me over to her desk. The teacher asked me why I left her classroom yesterday and I found out that I left her class of second graders alone in their classroom! I told her that I was sorry and that I must have forgotten. She asked me what happened and I told her that a short time after she left, my case manager found me and asked me to go to a fourth-grade classroom, which I did. It seems that I had forgotten that the teacher wasn't in the classroom! She told me that she had to leave for a few minutes and asked me to stay. She said that everything was fine, but she just wanted me to know. Luckily, I think that she returned to the classroom soon after I had left. I'm so glad that nothing happened and the students stayed safe.

I was horrified to know that I could have done this, but knew that I had. I've been doing my job for seventeen years and I don't believe that I've ever done this before. I'm shocked that this even happened and I'm quietly upset about this! I can't even believe that this happened!