It's perfectly fine to cry over the loss of a family member. Lost one myself in '10, and she was a rescued feral. I sat up with her all night long; it was the first time she had ever willingly let me pet her. Took her to the vet in the morning of that night, and they couldn't do anything for her but put her down. I bawled all the way home.
I'm sorry for your loss.
I'm sorry for your loss.