Diana says she knew the sex of Prince Harry before his birth, but chose not to tell her husband.
"He wanted two children and he wanted a girl," she explained. By keeping the knowledge a secret until the delivery, the letdown came as a complete surprise.
She recalls Prince Charles initial reaction was, "Oh God, it's a boy," followed by, "and he's even got red hair."
She told Morton that after Harry's arrival, "something inside me closed off," especially since her husband continued his affair. "By then, I knew Charles had gone back to his lady," Diana said referring to Camilla.
The two eventually separated in 1992 before divorcing in 1996.
However, Diana attributes the split to Charles' affair, not the birth of their second son.
"There were three of us in this marriage, so it was a bit crowded," she famously said in a 1995 BBC interview.