Los Angeles - Kris Jenner only found out Bruce Jenner was transitioning into a woman at a recent family meeting.
The showbiz matriarch reportedly "flipped out" when her ex-husband - who she split from in 2013 after 22 years of marriage - told her and the rest of their family he wanted to change gender because she was stunned by the revelation, even though she had heard speculation about his plans.
Insiders say Kris never asked Bruce about the rumours and he never told her, highlighting the "serious lack of communication in the marriage."
TMZ reported that during the family meeting, the 59-year-old reality star confronted her former spouse as she disbelieved the speculation, prompting a furious row as the Olympian insisted he is both "comfortable and determined" to see through his decision.
It was previously claimed Kris "cried a lot" after the meeting but now supports him "100 per cent".
A source close to the Keeping Up with the Kardashians star said: "Kris had the most difficult time of anyone in the family. She has had a lot to process. She has cried a lot about this, because it's an emotional thing for her.
"She's come back around. She has gotten used to the idea. She was most upset because it was the great unknown, but she has really been reading up on things now, so she'll know what to expect.
"It's really a hard adjustment and a shock, but Kris 100 percent supports Bruce. The whole family does."
Bruce - who is said to be the happiest he's ever been - will discuss his life-changing decision with ABC news reporter Diane Sawyer in an interview set to air in May.
However, his family will not be opening up about Bruce any time soon as it has been claimed they have decided not to do any publicity interviews ahead of the forthcoming new series of Keeping Up with the Kardashians.