Writing the letter made you feel better. Sending it will ultimately make you feel worse. Tear it up. I have a brother who does exactly the same things as yours. In fact, you might as well have been writing a description of my brother as yours. I refuse to discuss politics with him and NEVER answer any of his angry text messages. Ironically, that seems to be the most cruel thing I could ever do to him, since he is obviously frustrated to the point of madness because he cannot goad me into an argument. But when the family gets together, we can still hug each other.
Tear up the letter.
Life is like a purple antelope on a field of tuna fish...
