You sound like me, being calm, being strong, being brave for everyone. You won't grieve, you need control right now. Inside it's different and it won't come out for quite a while. Took me a month after my dad passing to finally greive, cry. I didn't do it in front of anyone either. Walked down through the woods to the river, got drunk(at that time only way to release any emotions at all) then It hit, I spent the afternoon screaming at god, my dad, my self, crying, laughing, a torent of all I pent up and kept hidden from everyone. The chipmunks, coons, foxes and squirrels must of thought I lost it that day. Just my way of grieving and I suspect a little you might do the same. Keep us posted.
PS If he is sleeping, coma, than he is dying in peace, that must a little, be a comfort to you. Remember self care too!!!!!. Hugs, big big ones