Who says you have to stop caring? He's a person you love with a sickness. I think it's great that you care and want him to be ok and this is so new, of course your emotions are all over the place.
Get through these first stages of shock and grief first and then it's possile to apply detachment and feeling happy he's gone.
You will be fine, you'll be more than fine, just take it moment by moment.
My ex had some shocking actions and when I discovered his secrets, it took me weeks to absorb it all in.
Keep posting