The song is about a guy who is heart broken over his wife having cheating on him. Hello there the Angel from my Nightmare. That is him thinking of his wife, her cheating on him has created a nightmare. He goes on talking about being a victim, that she is a shadow in the background of the morgue, which means she is killing him. The Jack and Sally stuff is him saying he thought everything was great and doesn't know why this has happened.
The second verse is him wanting his wife to come back to him because he misses her. That's why she's the voice inside his head. When something like this happens to you its destroys your life and becomes something that ingulfs all your time thinking about it.
The creeping and the hauting is her doing this behind his back and the webs from all the spiders is him thinking back about things that he missed, things that he could have caught. These things will eat you inside and that's what he says. The voice of treason is talking to her while he knows she is with someone else. That's why he wants her to come home and stop the pain tonight!
Hope this clears it up for you. I have had this happen so I look at the song differently.