My cat was sick and my mom took her to the vet to get her looked at, and she would be put down that very visit. I was never told this, I never got to say goodbye, didn't even know it was a possibility.
I didn't even know it happened. It wasn't until days later when I saw a vase of flowers on the kitchen table, and I happened to ask where they came from and what they're for, and was told they were from my mom's friend for the passing of the cat. That's how I found out about it, and my mom said she thought I knew and just didn't want to talk about it, thinking I would notice that her food dish wasn't on the floor anymore.
I never got to say goodbye, weigh in on our choices/options, or anything like that and it tears me apart inside just thinking about it, even typing this makes me sob.
My mom apologized to me, but I couldn't even bring myself to accept it or do anything resembling the sort, I would just stand there quietly before walking away. Its something truly unforgivable that I think I will hold onto forever.