There's no good way to lead into this without making the reader freak out: I've been thinking some lately about murder-suicides.
Not like I'm thinking of staging my own or anything. But I wonder why people do it. I get the suicide part; it's the murder part that leaves me scratching my head.
Following last month's Germanwings crash, the conventional explanation was that the pilot was so depressed he crashed the plane. I saw a tweet that said, in essence, "Years of living with severe depression has made me want to hurt myself, but never made me want to hurt someone else." I agree. I think the conventional explanation shows that most people still don't understand depression and are quick to believe false narratives that rely on their prior misconceptions.
But then how to explain the murder-suicide? Here's what I've come up with. A depressive wants to kill himself, but he is too cowardly to do it. He knows it's going to hurt, and he's afraid that, no matter how bad his life is, whatever comes next could be worse. So he steels his nerve by doing something so heinous that he will no longer hesitate to kill himself. Also, in a bizarre way it takes care of feeling guilty about leaving a grieving family. Also, he's crazy so it doesn't have to make sense.