was one of the novels I had in mind and the book does indeed have the passage you just mentioned (it helps to have a copy handy). I am incorrect about the passages in that novel, but I think it's kind of a moot point now compared to the other issues we've been discussing. If the Emperor thinks Vader killed his own wife it's still something he deliberately used to break Anakin's spirit and complete his destruction and conversion, and did so with glee as evidenced by his wide, satisfied smile when Vader breaks down with grief and lashes out from the medical reconstruction table.
Palpatine was still a nasty enough bastard to use that information to his own selfish ends....to secure his new apprentice and make sure he had nothing else left to live for. His mother was gone? The Republic had failed? Friends and fellow Jedi betrayed him? Wife dead at his own hand? His child perished with her? What else did he have except Darth Sidious, the Sith philosophy and their new Empire?
He was now the Emperor's tool to mold as he wished.