Complex sentence: As her arthritic pain increases, Kate comes to rely more and more on him and when she realizes that he is extorting money from her, she commits suicide, but not before turning him in to the sheriff.
Split into simpler sentences: As her arthritic pain increases, Kate comes to rely more and more on him. When she realizes that he is plotting to extort money from her, she commits suicide, but not before turning him in to the sheriff.