Sentence:  He did not really want to kill , but as in the <WSD>sexual</WSD> act , there was a moment when the impulse took over and could not be downed , even while you watched yourself giving way to it . 
Meaning of the word marked with <WSD> tags:  the act of sexual procreation between a man and a woman; the man's penis is inserted into the woman's vagina and excited until orgasm and ejaculation occur