If you want to see how dark things truly became around Garcia and the Dead, read "Dark Star: An Oral Biography of Jerry Garcia." Robert Greenfield interviewed dozens of people, including Mountain Girl, various Garcia ex-wives and girlfriends, band insiders (Justin Kreutzmann), Barlow, Bear, Scully, Ron Rakow, Garcia's childhood friends, his brother Tiff, David Nelson, Sandy Rothman, David Grisman, Merl Saunders, John and Linda Kahn, road managers, lawyers, GD office staff members, housekeepers and doctors, and constructed a spellbinding narrative about Jerry from the time he was a little kid right up until the end. The man was an absolute enigma, especially to those who knew him better than anyone. Fascinating read. The narrative is completely in the exact words of those people and it is mesmerizing.
Jackson's book pales in comparison (although he did use Greenfield's book as a source for numerous quotes). I re-read both recently.