Kim Kardashian West has revealed her mother Kris Jenner has been questioning if her "memories were real" with Bruce Jenner since he announced he was undergoing gender reassignment.

Kim Kardashian West and Kris Jenner

Kim Kardashian West and Kris Jenner

The 34-year-old star has admitted Bruce's decision to become a woman has been tough on her mother and left her confused about whether the couple were living a lie throughout their 24-year marriage - which produced two daughters, Kendall and Kylie Jenner.

Kim took to her Twitter account to tweet as she watched the first 'Keeping Up with the Kardashians: About Bruce' episode about his sex change on Sunday night (17.05.15).

In an emotional post about Kris, she revealed: "Breaks my heart my mom questions if her memories were real. That was 4sure a part of Bruce's life. Must be hard to go thru this as his wife (sic)"

Kim - who is married to rapper Kanye West - admitted she was tearful throughout the powerful episode but is so proud of Bruce and her family for dealing with the issue in such an open manner.

In a series of posts, she wrote: "West coast tune into E! I'm watching KUWTK About Bruce! ... The most emotional ever! ... Awwww the tears! Watching this back & reliving this is harder than I imagined! I'm happy we opened up & shared our journey ... WE WERE VERY OPEN IN HOPES TO HELP OTHER FAMILIES GOING THRU THIS (sic)"

Kim also praised her stepfather Bruce for being brave enough to make this life-changing decision now and for the way he has handled it with each one of his kids and stepchildren.

She tweeted: "Must have been so hard for Bruce to explain his story to each of us. Can u imagine?! I respect him so much 4 opening up & being so truthful (sic)"

The second episode of 'Keeping Up with the Kardashians: About Bruce' will be shown this Sunday (24.05.15).