I think there is some confusion here between Anna Ashe; who was killed by the Skavis (Pricilla) in White Night, and Hannah Asher who we remember as the super skilled fire wielder and also a Denarian from Skin Game; who we thought died under a couple tons of molten rock, but apparently not.
It was Lara who manipulated the campaign to kill minor magical talents into being; to pit House Skavis and House Malvora against one another, even though it was the head of House Skavis who actually ordered it and sent his heir apparent to carry out. This makes Lara ultimately responsible for the deaths of Anna and the other women killed by Skavis and Malvora.
It is a bit confusing because we don't really know the details, we know that Lara only weakly contested Harry's accusations that she was responsible by pointing out that Lord Skavis had promoted a similar plan a century earlier. She never said, "I didn't do it."
I think Harry would be disturbed that he truly enjoyed Lara's company, but not because of any one or several deaths she has caused. Harry knows that Lara must be responsible for hundreds of deaths in her lifetime. Harry has often pretended that the only reason he is attracted to Lara is because of her White Court mojo, but being forced to recognize his attraction is deeper than that; and I'm not talking about true love, the fact that Harry genuinely likes Lara and likes spending time with her would be disturbing to Harry.
Harry has always been hard on himself. Harry would question if enjoying spending time with a monster; a beautiful, intelligent, charming, fun loving and polite monster, but a monster none the less, would mean that he is losing his battle to remain himself and not give in to the pressure of the Winter Knight's mantel or give in to Mab's schemes to mold him. I think Harry would worry that he is taking another step into becoming a monster himself.