I forgot to label a med in clinical once.
Technically, my preceptor drew it up while I watched and then left it for me to give with my instructor - common practice where I was.
All hell broke loose when my instructor came in and I tried to give an unlabeled med that someone else drew up. It threw me for such a loop, and made me so anxious, I couldn't function and I ended up being sent home for the day with a big, fat F.
Ah, memories . Just remember...eventually all this will be a distant memory.
As other people have pointed out, yes, you have to label meds, and YES, you have to be responsible for your patient, even if your instructor is pushy and gets in your way. I know I struggled with really being "in control" and taking full responsibility when I was in clinical (too many irons in the fire, not enough time for me to process without other people jumping in), but it's something to work on.
Don't beat yourself up. You're there to learn, and lots of lessons are leaned by making mistakes.
As far as her behavior, it was totally inappropriate to talk to you like that in front of your peers, and you're right...she could've took the time to educate you, vs whatever she did. I had an instructor like that in my 3rd semester. I burned her effigy in our graduation bonfire.