Spock did not say the Pon Farr would kill him He said he would be driven to return home, take a wife or DIE IN THE ATTEMPT. McCoy is the one saying the pressure would "simply kill him". I my humble opinion Spock had already slept with Christine Chapel. He says to her one "I cannot give you what you want" He didn't mean sex, he meant marriage (He was already married). Christine's obsessive love for Spock clues me into this. This is part of natural Vulcan telepathic sexual bonding. I think the women of Vulcan had and have a huge problem with males.
It isn't just violence. It's that they have the mental powers to get sex from women. Spock demostrates this. He continually rejects Christine, or treats her coldly and she keeps coming back. Even after a 2 year absence it isn't over for her. I know people hated Majel Barrett in the role, but for a moment imagine a more winsome, feminine actress as Christine. Also, when Spock announces on the bridge that T'Pring is his wife, Christine gives Uhura a look that says "that bastard lied to me!" Spock and Christine were and probably afterward were intimate too.