A harrowing chapter about death - in A God in Ruins

Kate Atkinson continues a run a truly impressive chapters in A God in Ruins, it's tempting to say each could stand alone as a story but I don't think that's quite true in that part of their efficacy and beauty is how carefully and thoughtfully she has built up the background of each of the characters, Teddy especially. The chapter I read last night brought us at last to the early death of Teddy's wife/Viola's mother, Nancy - hinted at and alluded to in many early chapters, though never quite explained until this late chapter,when we see her suffering from and dying from brain cancer. Those of us who have witnessed this disease will be particularly moved by this chapter, of course, but it speaks to a universal fear and horror, of literally losing control of one's mind and one's perceptions. The chapter concludes w/ the harrowing scene, deftly shifting in and out of Nancy's consciousness, as she plays the piano - she thinks she is at last playing beautifully a difficult Chopin piece but as we shift outside her pov we recognize that she is just smashing her hands against the keyboard, deeply upsetting young daughter, Viola. Then in an even more astonishing scene, which Atkinson develops very carefully, laying the groundwork early on, Teddy comes through on his promise to kill Nancy if needed - in this case he follows one of her suggestions, which he initially said he could never do, and smothers her in a pillow - and then we realize that Viola is watching this action, which must be incredibly traumatizing and helps explain her difficult life-long relationship w/ her father. Terrific scene - but I do have to raise a quibble with this section, in that I found it impossible to believe that Nancy would go off for various treatments and consultations while lying to Teddy and telling him she's visiting her sisters. That's so unlikely as to seem like an author's trick to build tension and mystery - a rare mis-step by Atkinson, in my view.