Mattie Blaylock was Wyatt's second "wife". Josie/Sadie Marcus was his third.
I believe that "I Married Wyatt Earp" had some credibility issues and is often classified as fiction.
Wyatt Earp was never formerly marrried to Mattie Blaylock.
Josephine Marcus Earp, although never formerly married to Wyatt Earp, spent the rest of her life after Wyatt Earp died, trying to polish Wyatt Earp's reputation.
The Marcus book has many fictional sequences in it, as do all books about famous westerners of that era. Read Stewart Lake's book about Wyatt Earp, if you want to read fictional prose. Lake couldn't get his book published, due to Josephine Marcus Earp's opposition, until after she died in 1944.
Both Wyatt Earp and Josephine Marcus Earp, had severe addictions to gambling.
One thing that I don't understand, is why people demand their western heros to always be the guy in the white had...! Nobody, then, or now, can stand up to the scrutiny that readers want to subject their heros too. They were men, subject to all the temptations and vissitudes that all of us are subjected too.