unforseen feelings in writing

I seem to have a bit of an ethical writer's block. Let me explain:

I'm trying to write a Film-noir like story set at the U, and in one scene our hero (or rather, anti-hero given that it's film-noir) heads to Wilson library to get info. from bums. Well, as I'm writing this scene, I can't help but actually feel sad. I mean, I do genuinley feel bad for homeless people. So yeah, it's just a tough scene for me to write. Gets me thinking on how some authors wrote stuff that was even worse...how did Doestoevsky feel when wrote the murder of Lizaveeta in "Crime and Punishment?" How did Hemingway feel when he described a massacre in a Spanish village in "For Whom the Bell Tolls?" And so on.

That's all for now. Hopefully when I work on the "Iowa Lyon Series" I won't run into these same spiritual barbs.