It looks like your sentence got cut off after “people use to…”. I can continue it in a few different directions depending on the tone you want.
Here are a few complete versions:
1) Dramatic continuation
Mrs. Barragán dropped the bomb on the sidewalk with the same calm tone people use to comment on the weather, as if what she was saying didn’t crack the world open beneath our feet.
2) Emotional / story-driven
Mrs. Barragán dropped the bomb on the sidewalk with the same calm tone people use to make small talk, and for a moment, no one understood what she had just changed forever.
3) Suspenseful / thriller style
Mrs. Barragán dropped the bomb on the sidewalk with the same calm tone people use to ask for directions, and it took a full second before the meaning of her words hit like a shockwave.
4) Subtle but intense
Mrs. Barragán dropped the bomb on the sidewalk with the same calm tone people use to talk about ordinary things, but the silence that followed was anything but ordinary.
