It is difficult and problematic to talk about your illness to children, especially if it is a serious illness such as cancer. Parents often think that it is better to remain silent with their children because they would not understand, they would suffer too much or they might be shocked.
Children's ability to face the truth is often underestimated by adults, but children tolerate the truth, even if serious, better than the uncertainty of not knowing. It is essential to find the right time and the right place to talk, preferably in the presence of the other parent.