The age-old question of why this sort of thing doesn't happen to horrible people is a really hard one to deal with.
Some people will believe it's "God's plan", others that it's just random, and others that it's Fate and it's been written this way for years.
Who knows? Too many awful people still manage to live long and healthy lives, too many good people die too soon from disease (including your Little Hubby, because it was his disease that got him :( ) - no one can say why.
All we can do is, eventually, accept it is just the way it is and carry on doing what we do, with that extra little bit of "life learning" that is the pain of loss. But you're not there yet - you're still in the early stages of the process, and one of the things that it is important to remember is that the 5 stages of loss/grief don't happen in a linear fashion (except possibly the last one happening last, which is acceptance).
Do you have an old jumper of your Little Hubby's that you could give to the cats for their own? That might comfort them.
Sorry, not sure my philsophising on this front is any use at all - I know when my Nanna died of a heart attack I spent a long time railing at the situation, wondering why other people got to survive their first heart attack and she didn't; same when my mum died of colon cancer - why her? But there is no why. It just is. :(
(((hugs))) and
and 