Chilling ending, and the visual images very strong throughout. I don't know if you made edits since the comments above, but I'm also a long sentence writer (and a sometime-professional editor who is pretty hyper about grammar and structure) and I didn't find you having run-ons. In fact, I enjoyed the contrast between the longer sentences at the beginning, which give a more meditative pace, and the shorter sentences when the twist is revealed, which is pretty much classic thriller structure.