killed my first mouse today and i’m dying inside. just me?

i just feel horrible! i’m an undergrad and have been with my lab for 3 years, so i knew this day was coming eventually, but i had no idea i was being trained on euthanasia today. like the idiot i am, i spent half an hour learning how to scruff them and commenting on how cute they are until the trainer says i’m “ready to move onto stage 2 of training” and brings me to the necropsy room 😭 my brain just keeps replaying the image of them being gassed and having to do cervical dislocation by hand. it was upsetting, but was relatively fine when i came home. but later on in the night, i was sorting through my boyfriend’s pokémon cards and saw Tandemaus and immediately broke down 😭😭 i know it’s stupid but i’ve been crying for the last hour and a half i just feel so bad and off. like i just cant believe i’ve purposefully killed a living creature. am i alone in this?