Kim Kardashian has tearfully admitted co-parenting with Kanye West is "f****** hard".

The 42-year-old reality star - who has kids North, nine, Saint, seven, Chicago, four, and Psalm, three, with her ex-husband - has opened up on the way she's trying to raise her four children with the 45-year-old rapper.

Appearing on Angie Martinez's 'IRL' podcast, she said: "It's hard. S*** like co-parenting, it's really f****** hard."

The reality star and SKIMS founder admitted almost one month after finalising their divorce, she is protecting her family by not telling her children about things going on "in the outside world".

She added: "I definitely protected him and I still will in the eyes of my kids, for my kids.

"So, in my home, my kids don't know anything that goes on in the outside world."

The proud mum admitted she will continue to protect them "for as long as [she] can", as she broke down in tears.

She added: "If they don't know things that are being said, why would I ever bring that energy to them?

"That is real, heavy, grownup s*** that they are not ready to deal with. When they are, we will have those conversations.

"One day, my kids will thank me for not sitting here and bashing their dad. I could."

She explained how they "don't know anything" about the situation, and she makes sure that is the case at school.

She said: "My kids don't know anything. So, at school, some of my best friends are the teachers, so I know what goes on at recess and lunchtime. I hear what is being talked about."

Meanwhile, Kim's approach means there are moments she has to put on a brave face for the sake of her kids.

She added: "If we are riding to school, and they want to listen to their dad's music — no matter what we are going through — I have to have that smile on my face and blast his music and sing along with my kids.

"[I can] act like nothing is wrong and as soon as I drop them off, I can have a good cry."