Bruce Jenner kept Kris Jenner in the dark over his sex change until their family meeting several weeks back ... and she flipped out because she just couldn't believe the man to whom she was married for 22 years wanted to become a woman.
Family sources tell TMZ ... Kris heard all the buzz about Bruce but he never told her and she never asked. It sounds incredible, but we're told there was "a serious lack of communication in the marriage."
When they had their family sit down -- which of course was recorded -- we're told Kris squarely challenged Bruce, disbelieving he truly wanted a sex change. Things got heated because Bruce insisted he was both comfortable and determined.
We're also told Kris felt this was a shining example of the fundamental problem they had in their marriage -- they hardly communicated with each other, and Bruce was especially shut down.
But Kris was not singled out. Bruce kept virtually everyone in his life -- including his close male friends with whom he spent lots of time -- in the dark.
You may recall, when TMZ posted the story in December 2013 that Bruce was getting a laryngeal shave, he told us he absolutely was not undergoing a sex change. We were told otherwise at the time but Bruce was adamant.
It was all part of his plan to gradually let people get wind of what he was doing so it wasn't an enormous shock.