My father (who is now deceased) was stabbed in the back by his own family. My father and his father had a falling out and were not talking for a while, he removed my father from his will (my grandfather was extremely wealthy) and when he died, all of the brothers except my father were named on the will. That crushed my father, and the 3 brothers said they would split it up, they did nothing.
They were living their life style in large houses, they had full control of my grandfathers land and sold it off, etc. When my father died, at the funeral I didn't want to speak to any of them. They made all kinds of promises how they would help us get through any financial problems we were having, and didn't even bother to give us a phone call.
While it wasn't specifically stabbing me in the back, our own family stabbed my mother, father, brother and I in the back. I still don't talk to them to this day and as far as I'm concerned I really don't care what their up to these days. That's a major reason we moved as far away from my fathers family as possible.