How can I stop thinking about all the horrible things in life?

I feel like I have been obsessing on why people abuse children and animals. Just thinking about it makes me cry and cry my eyes out. I know it's not healthy for me to think about it all the time but I just can't stop. I just want to save every child, animal, and person in need in the world and I can't. It's very frustrating and I wish more than anything these kind of things would never happen. I can't sleep and when I do I have nightmares every night. Why can't people just be empathetic and compionate? What to do?