Did anyone read the book?!

Yeah, maybe. I just saw the film on DVD again and listened to the director's commentary. I remember all the PR surrounding this film and Kim's book. So I have to say, "check the credits" and only Kim's book is credited, it was bought in "pre-sale" as a manuscript for a movie. These are what I read about these events and Kim's book and this movie. So that's my answer to that inference.

It's been way too long since I read the book so can't answer that question.

I've never read the book, I guess it's a fictionalized version of the real events, where as Smith County Justice was the non fiction version. But I saw this summary of the real events that I thought was interesting (from a court case where her ex-husband/partner tried to sue over the money she made from the book and movie):

Prior to 1979, Creig Matthews was an undercover narcotics officer with the Plano, Texas,
police department, in charge of the criminal investigation division. Kim Wozencraft (Kim Ramsey
at the time) was hired as a police officer. Matthews trained and then worked with her as an
undercover narcotics officer making drug purchases. Both of them used drugs, primarily marijuana
and cocaine, while on the Plano drug assignment.
In August 1978, Matthews was hired by the Tyler, Texas, police department as an undercover
narcotics officer, where he used the aliases "Jim" and "Jim Myers." Early the next year, Wozencraft
joined him in Tyler as an undercover drug officer. Together they conducted a drug investigation that
lasted until April 24, 1979. During this time, they became romantically involved and began living
together.
Their primary target in Tyler was Ken Bora, for whom Matthews worked undercover as a
bartender. After several futile attempts to buy drugs from Bora, Matthews and Wozencraft,
on instruction from Tyler police chief Willie Hardy, made a phony "stash" case on Bora.
During the investigation, Matthews and Wozencraft used drugs both to make drug cases and
for personal use, eventually becoming addicted. They informed Hardy of Matthews's drug problem.
He gave them several days off but insisted that they continue with the investigation. At the end of
the Tyler investigation, Matthews and Wozencraft assembled over 200 drug cases, involving the
arrest of 100 defendants.
At the conclusion of the investigation, Matthews and Wozencraft were attacked by a
shotgun-wielding assailant at Wozencraft's mobile home. She returned fire and was not seriously
hurt; Matthews was severely wounded in the arm and leg and was hospitalized for over a month.
After being released from the hospital, Hardy placed them in a house on the outskirts of Tyler. While
there, they were visited by H. Ross Perot, who at the time was serving as chairman of a special crime
commission. Perot moved them to a secure safe-house in the Dallas area and arranged for Matthews
to receive medical treatment for his wounds.
During this time, Matthews and Wozencraft began testifying at the trials of some of the drug
defendants. They falsely denied using drugs during the investigation and falsely testified that they had
bought cocaine from Bora.
Evidence arose of their misconduct. Eventually they confessed, pleaded guilty to criminal
informations alleging civil rights violations, and were sentenced to terms in federal prison.

Casting for movie in the Dallas area titled "Sluts" - theslutsmovie.com