If you figure out the secret before the reveal, is it still a secret?

Tessa Markham arrives home on a rainy Sunday night to find a young boy sitting in the kitchen of her locked, and otherwise empty, London flat. Instead of calling the police, she calls Scott – her estranged husband and father of her dead twins.
The Secret Mother by Shalini Boland tells Tessa’s story as the boy Harry is picked up by the police and returned to his father. As the story unfolds we learn of the tragic loss of Tessa’s children, her mental breakdown, and separation from Scott.  Suspected of abduction, Tessa fights to clear her name and uncovers information about Harry’s family that leads to the eventual discovery of why these two seemingly unrelated lives came together.
The Secret Mother is a quick, predictable read. I had the story figured out before I hit the halfway mark, disappointing for something billed as a “gripping psychological thriller”. The plot points are almost laughably formulaic: a twin lost in childbirth; a grieving mother whose grasp on reality is questioned; an estranged husband with a beautiful and younger new girlfriend; a missing boy with a dead mother and a physician father (gee, I wonder where he worked a few years ago….?); a mystery woman following the main character; a neighbour who is also conveniently a nosy reporter looking for her next scoop. I finished the novel’s “climax” wondering if I had accidentally skipped a few paged and missed the twist that other reviewers online had raved about. Or maybe the twist was that the reader would never be told why the nosy neighbour had been sneaking into Tessa’s home using the hidden house key ….
I was also put off by the first person narrative, which I often found clunky and basic. Perhaps the POV was taken to try and immerse the reader into Tessa’s mindset; I personally found it made her less sympathetic and only served to highlight her flaws. I don’t think the author wanted the reader to roll their eyes as much as I found myself doing.
The Secret Mother by Shalini Boland receives an unfortunate 1 star from this reviewer.