i would hazard to guess that you're functioning at a relatively "normal" level despite this because you've already come near to losing him once, and recently, and began a grieving process then. since that time you have psychologically steeled yourself for this eventuality, and probably come to some peace with it.

that's not something to beat yourself up over, even if me saying that doesn't stop it from happening. cats, even sick cats, can sense distress in their loved ones. your lack of *extreme* distress can only serve him well.