The narrator is Esther's husband. He speaks of Esther being killed in a drunk driving accident or a brake system failure. The drawings on the walls are scientific depictions of brake system failures and drunk driving. At the end, he says "come back" because you (Esther), are in a coma and the plug is being pulled, thus the BEEP at the end. Hope this helps with the confusion...
This aside Dear Esther is a fine experience.
I'm kinda bothered though with what people opinions are about this, mainly because there's always that guy that begins the inevitable debate of "See!? Video games are art!" and okay that's great and all but why video games have to be like something else? Is because people can't understand video games and they need other medium as an example to understand how great and profound the experience was?
More importantly, I wonder what was the game that started that whole debate in the first place.