You asked for reviews on this story, so here goes.

You're a good writer. Your prose is solid, and, while the content might be a bit too gritty and grisly for some, I think your setup more than justified the dark tone of hopelessness, which is all that matters.

While David's condition doesn't change much (he starts out pretty close to rock-bottom; there's not much left for him to lose), the steady progression he witnessed in the condition of the cat's corpse is all the development you need. You satisfied what I consider to be the only real task facing an author: you made me want to see what happens next. Of course, in the back of my mind lurked the thought, I like where this is going. Hope he pulls it off.

Alas, you don't. Having brought the events of your setup to the point where actual plot complications need to kick in, you simply throw up your hands in defeat, kill off your main character (in whom we've invested all our emotional and psychological involvement) and bring in two strangers (to whom we owe nothing) and have them merely recount to each other the things we already know, at which point they, too, throw up their hands in frustration and give up.

Truth is, I can't say whether or not you have the instincts to craft a real development and third act for this. What's obvious is that no one gets to write prose by accident that sounds as accomplished as yours. You've spent time at your craft. Unfortunately, the kind of savant-like ability to wring a plot out of the most mundane of events evidenced by someone like Stephen King (whose early short stories you clearly are channeling, consciously or not) can't simply be willed into being.

Inspiration comes to mind, and while I'm no better at defining it than anyone else, that's what's called for. Do what you must to eliminate the conditions that might prevent it from visiting you (such as giving in to your impulse to cheat the reader and yourself with shortcuts that fool no one) and try to visualize what the real implications might be of the events you've so convincingly set in motion.

I won't suggest where you might take this; it's not my story, after all. But it deserves to be finished. I hope you're up to it.