Mark Twain said something similar to this, however, I have been unable to find the quote. I would offer one small correction though.
Jenny set me straight. A very nice girl and a fine bloggy friend!
"It takes your enemy and your friend, working together, to hurt you to the heart: the one to slander you and the other to get the news to you." - Mark Twain
When the enemy and the friend are the same person, this of course has to be your own brother.