[Spoilers] Question about Mary’s letter

Okay so I understand the letter that James come in with is a fake. The actual paper is a blank page which is revealed at the end. A couple questions though

1. Is the letter a manifestation of Silent Hill or of James being psychologically broken? I guess in a roundabout way you could say both but I am moreso wondering if James would have “gotten the letter” even without Silent Hill’s supernatural aspects because it was in his head.

2. Is the letter that is read by Mary in the ending (idk if it’s unique to the Leave ending or not but it is the one I got) the real letter that Laura would have had if she hadn’t lost it? Is that letter real? Does Laura find it? Does James somehow receive it or does only the player get to know what was on it?