Complex sentence: It is mentioned in Tex that Cathy Carlson later went to his funeral, as she is a teacher at Tex's school, and saying that Mark was not a friend, but someone whom she knew a long time ago.
Split into simpler sentences: It is mentioned in Tex that Cathy Carlson later went to his funeral, as she is a teacher at Tex's school. When Tex discusses Cathy going to the funeral she tells him that Mark was not a friend, and that she knew him a long time ago.