Is it normal this affected me so much?

I was cutting the grass earlier when I got to some long grass, as I was cutting it I saw something move so I immediately turned it off,

I'd caught a frog with the blades, it's legs were half bone and there was a long cut down its side so it's intestines were hanging out on to the grass yet it was still trying to hop around.

I knew it wasn't going to last long, it was failing to hop by this point so I decided to put it out of its misery quickly, I grabbed a spade and hit it about 4 times just to be sure.

It made me feel sick, I felt so fucking bad and I haven't been able to stop thinking about it since, I was having dinner and the site of its guts hanging out kept coming back and put me off my food,

But at the end of the day it was a frog, but I feel like I've killed a pet, is it normal that I'm so affected by this?