I'm a bit late getting to this thread (stupid ISP!), but I feel the need to pass on my condolences. I can't imagine how it must feel to watch a furry friend die like that. Every time I've lost a pet I haven't had to see it first-hand.
I'm so sorry about your loss. I've got myself a little female kitten 8 months old exactly and while I was reading your post, I looked over my Yuffie and felt this pain in the heart like it was being stabbed or something. I can relate to your feelings right now, because I've always had pets on my life, thought just birds and small rodents, even so it's really painful when a pet of yours dies and you end up being unable to do a thing to help the little guy.