Stepmom (1998)

Jackie and Isabel have nothing in common--one is the ideal mother, the other is struggling to be any kind of mother--until circumstances force them to share a family and put aside their mutual hostility for the sake of the children. They discover how precious life, love and the ties that bind them really are in this tale about the intricate circumstances surrounding what happens when a man's new wife learns from his former wife that she is terminally ill with cancer.