Complex sentence: While Shawn and Isabelle are talking Devon interrupts telling him that he has a visitor, Shawn discovers it is Nikki who has come to visit him, she tells him of that her father has become ill with cancer in his pancreas.
Split into simpler sentences: While Shawn and Isabelle are talking, Devon interrupts them telling him that he has a visitor. She tells him that her father has become ill with cancer in his pancreas.