EXCLUSIVE

He definitely saw this coming ... but now Atlanta Falcons owner Arthur Blank has been hit with divorce papers from his estranged wife ... TMZ has learned.

Blank -- the BILLIONAIRE who co-founded Home Depot -- had previously announced he and Stephanie Blank separated in 2011 ... after 16 years of marriage.

Now, Stephanie -- the mother of Arthur's three children -- has pulled the trigger ... filing divorce docs in Fulton County, GA.

According to the papers, Stephanie claims the union has been "irretrievably broken" ... but the good news -- the two have already hammered out a settlement that covers money, custody and property.

The terms of the settlement are confidential -- but with Art reportedly worth $1.3 BILLION ... Stephanie stands to get some serious green.

As for the couple's three minor kids ... Stephanie says she and Art have put together a "comprehensive Parenting Plan" ... but the terms of the plan are also confidential.

Back when they split, the couple had released a joint statement saying they "remain great friends and are committed to working together to parent their three wonderful children."