old english saying that was used to announce that the person in question was disowned or would never be "seen, or heard" again.
you slept with my wife.....you're dead to me
the origional aiel used the term in a Robert Jordan book as well, but in a more wordful way
"You killed some one, you are dead to me and the rest of the True Aeil......Turn away from me i wish not to see that face, my son had a face like yours, but alas he is dead to me?
A phrase, if used too often and with poor discretion, that eventually loses its initial impact.
Mortimer: Ethel, if you don't pass me that pan of steamed asparagus, I'm serious this time, you're dead to me.
Ethel: Give it a rest, Mortimer.
To be used to tell someone off when someone tells the dirtiest joke you can possibly imagine.
Wanda: Why are little girls better than little boys? You can flip her over and then they look just the same.
Boss: That's the dirtiest joke I've ever heard. You have completely wrecked my plans to ask you out on a romantic candle-lit dinner, nail you, and finger guns to our fellow employees. You're dead to me. And you're fired.