Anybody who didnt spay/neuter their cats?

Just wanted to ask. I know most responsible thing is to spay/neuter our cats but we are now traumatized as we had our 2 year old cat neutered a month ago and he had allergic reaction to anesthesia and so he didnt make it…. Would like to hear if any cat owners had experience of not spaying or neutering their cats and if yes, how’s your cat now and what did you do to make sure they’re healthy even if not spayed?