The speaker describes falling "into a hole of books," as if reading were a kind of accident, something you tumble into rather than choose. The title, "Bibliomania," names the obsession: a love of books that has grown into something close to madness. Once the speaker is down in that hole, the line between stories and real life blurs. "Everything" starts to feel like it belongs on a page, and the most striking example comes in the third line: "even my wife."
That line is where the poem turns. Placing a wife alongside everything else that "happened as in a book" is both funny and a little unsettling. It could mean the speaker sees the people closest to him as characters, or that his life has taken on a scripted, unreal quality. The poem doesn't say whether he is delighted or uneasy, and that ambiguity is its charm. The mood is dry, playful, and slightly dizzy, like waking from a long read and not quite trusting the room around you.