Every time a friend succeeds, I die a little.

Gore Vidal (1925-2012) American novelist, dramatist, critic

(Attributed)

In Wilfrid Sheed, "Writer as Wretch and Rat," New York Times Book Review (4 Feb 1973) and in The Sunday Times Magazine, London (16 Sep 1973) ("Whenever a friend succeeds, a little something in me dies.").