Darkness: Book One of the Oortian Wars

Lieutenant Jack Falco woke up, said goodbye to his wife and daughter, three hours later, his family and half the world's population was dead. When he couldn't put a bullet in his head, Falco did the next best thing, took a commission as captain and left for humanity's furthest boundary, Station Pluto. Five years in a scout-class boat refitted for the long haul, and Falco escapes the horrors of earth only to find something worse waiting in the vast Oort Cloud, an ancient civilization with a history of violent expansion and humanity has unwittingly entered their territory.