So… there’s almost no doubt that Harry killed Madeleine, right? His story about his first wife running off to Italy with a lover was super fake, and full of holes, and only someone as innocent as Violet could believe in it. Old Mrs. Weber was loyal and devoted enough to help hide a murder, and a respectable housekeeper explaining the tragic death in the earthquake to the authorities is a solid alibi.
I even thought for a little while that Mrs. Weber found out Madeleine was cheating, and killed her out of insane, OTT loyalty, but I take that back. Harry’s extreme jealousy and his reaction to Madeleine’s “reappearance” made it seem even like he’d killed her. But Madeleine is definitely dead, and 100% not in Italy with her boyfriend.