The story is finished. I left a lot of it kinda open like that because I think stories should always leave a lot of the storyline up to the reader to decide.
Tonja -- When I wrote it, I kinda was thinking that he killed her too. But again, I didn't flat out say so because there's something to be said for accidental death or whatever. Montag could be crazy, sure, or maybe he's just overcome with grief. It works either way, I think.
And hunter -- What you were saying about subtlety in stories makes sense, but I was going for the opposite effect. I find things a lot more interesting if there's kind of a 'mixed emotions' element; as in a really dark story told in a cheerful manner, or in this case, a story in which the somewhat jarring climax is told nonchalantly. At least that's what I was trying to do. It just makes it so much more interesting to me personally.