Okay, I can see that after you explain it here, and I did pick up on something going on with the bit in the TARDIS and Amy rescuing him but I didn't get the greater context of your explanation from the signposts in the story. And I agree it is quite difficult to convey the idea that River never existed at all in this reality; trying to explain an absence the character would never know existed from that POV is a task! (I have some beta-y thoughts about it; would you rather switch to PM?)

I do so love the Doctor's connection to the TARDIS; the way you describe the absence and unreality of everything to the Doctor's senses that results from her death is truly horrifying and heart-breaking.