This is a real long shot. But, your description made me think of Greg Bear's 1983 short story (later novel in 1985) Blood Music. In it, Vergil Ulam has created cellular material that can outperform rats in laboratory tests (an early form of organic based nanobots). When the authorities rule that he has exceeded his authorization, Vergil loses his job, but is determined to take his discovery with him.
In the novel, renegade biotechnologist Vergil Ulam creates simple biological computers based on his own lymphocytes. Faced with orders from his nervous employer to destroy his work, he injects them into his own body, intending to smuggle the "noocytes" (as he calls them) out of the company and work on them elsewhere.
The parts that reminded me of the story:
The author was talking about how his wife was in the other room in a cryptic manner. Then about some weird gory detail depicting the scene of his "wife's movements". He was talking in an unclear metaphorical way, as if he was comparing it to absurd ideas while also talking in a literal sense.
If you scan the screenshot excerpts below, you will see how the protagonist is describing the woman in the other room (though not his wife). It is extremely creepy.
There was something about a sentient robot / household robot? Suggesting that in his book, the world has robots commonplace? (The robot part I'm not entirely sure, it may not have that)
Inside Ulam's body, the noocytes multiply and evolve rapidly, altering their own genetic material and quickly becoming self-aware. The nanoscale civilization they construct soon begins to transform Ulam, then others.
It was a thin book
It was originally a short story. The novel was relatively modest in length. Only about 200 pages or so.
The author was talking in a strange, mysterious and scary fashion. Slightly came off as surrealist. He also hinted that his wife may or may not be alive / human. That was where the horror part came in.
See the excerpts below. The woman is no longer human but doesn't actually realize it. She also is not dead in a literal sense, but might as well be.