Same. I did not want to see my cat's last moments or breaths when I put him down, but I knew he was by my side through some of my most trying times, so I had to be next to him for his. Not easy, not easy at all.
It sucks, it sucks, it sucks, it sucks. I still feel the loss of a cat I had rescued as a kitten that got me through some very tough times. He passed almost 5 years ago. You'll get better at dealing with the loss bud, it will just take time.