Complex sentence: One deranged chapter lasts only a page-and-a-half, a letter, alleged written by a girl named'Xania' but obviously written either by Thompson himself or a fan with an extremely good imitation of his style.
Split into simpler sentences: One deranged chapter lasts only a page-and-a-half. It is a letter, allegedly written by a girl named'Xania,' but obviously written either by Thompson himself or a fan with an extremely good imitation of his style.