Sorry for your loss, DS. I know it's hard.
When I was little, we had a dog, Frosty. We were given a cat by one of my parent's co-workers. They didn't get along at all. They fought for a month. They grew out of it, and became best friends. When my dog died, my cat would stare out the window, hoping she would come home. Our cat became detached from us for the longest time. He wouldn't let me near him, and it just broke my heart all over again.