Agassi spills all about the couple's ill-fated marriage, which ended in divorce in 1999, in his candid memoir Open, confessing they were a terrible match and should never have wed.
The sports star recently admitted he clung on to the model/actress in a desperate bid to find happiness during an emotional breakdown.
He said, "(I was) 27 years old, ranked 141 in the world and in a marriage that I shouldn't be (sic) in... I didn't want to be playing tennis either, so my life was filled with things I didn't want, things I didn't choose. Part of it was an inability to find a place for anything really."
But Agassi felt obliged to contact Shields and get her input on his recollection of their doomed union, so he could present both sides of the story to fans.
He says, "I included her in the process. I had to navigate a lot of waters and I went to great pains to shine a stronger light on me, my goal was to be harder on me than anybody, but she's part of the process. We had a lot of similar recollections (but) our interpretations differed at times."
In his new book, Agassi also admits to taking crystal methamphetamines and deliberately throwing tennis matches.