as a child or overall? i guess if we are talking about my saddest memory from childhood that causes me a pain in my belly from thinking about it, it would be when i had to go to the vet with one of our ill dogs. he was old and had run away and gotten hit by a car so he had a fucked up spine and his prostate was swollen, causing him extreme pain.
he was my mum's favourite and because she was disabled, she could not come with us. when we got there the vet said that he would have to be put down. he was suffering quite a great deal. i spoke to mum and she agreed. i couldn't be in the room when it happened, so i waited out in reception. i still heard him yelp just before he died though and it was one of the most horrible sounds in the world.
i will never forget the look on my mum's face when i came home with just puppy's blanket in my hands. it totally broke her heart.