Steve lies dying, as Jack

Steve lies dying, as Jack, his law partner of 40 years, sits at his bedside.
“Jack, I’ve got to confess — I’ve been sleeping with your wife for 30 years, I’m the father of your daughter, and I’ve been stealing from the firm for a decade.”
“Relax,” says Jack, “and don’t think another thing about it. I’m the one who put arsenic in your martini.”