Bergamot,
Are you new to work? That type of situation is very normal in our daily life. I always tell myself that mistakes can happen to anyone, but you must learn from it and never repeat it again.
Life is too short and dont stress too much in tiny matter.
I hv been in this job for quite a few years la. My assistant was quite good, but since she started dating, she couldnt concentrate on her work. My boss has been like this for a long time!!!