feeling down and depressed

So I read this disturbing headline story about a nine month old baby girl getting assaulted and dying in the hands of the moms boyfriend and now I am traumatized by it, I have a 6 month old girl and all I can think about is how much pain the poor baby must've been in and it's affecting me greatly, I cry like 5 times a day and visualize what happened to her. It's affecting me and my ability to care for my child. First time mom. Do you guys think this is part of like postpartum depression?? I walk around sad and I feel like someone really close to me died or I knew her. Any help would be appreciated. What should I do to get over this??