She's just embarressed, she'll get over it. You've already said what oyu had to say, she heard you. Now just move on, don't keep bringing it up.
If she wants to further discuss it she'll come to you then go ahead, but if she doesn't then let it go. Make a joke about it and say...even if you think you're home alone, you still lock the door!
Just leave her alone, she obviously feels guilty. If you get a moment alone with her tell her that you still don't think it was a bad thing to have been doing and that you won't tell anyone, even if she pretends not to hear you that will eat away at her until she gives over.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.