Pilar Sanders' lawyer, Larry Friedman, tells us she was "heartbroken and surprised when [she] read ... that Deion announced his decision, on his own, to end their marriage."

Pilar's lawyer adds, "Pilar's sole focus and top priority for the last 12.5 years has been her marriage and children. Based on recent discoveries, [Pilar] now realizes that Deion did not view their family the same way."

Friedman would not reveal any details about the "recent discoveries" to which he referred.

Friedman tells us Pilar has NOT negotiated a divorce settlement with Deion -- but says she fully intends to protect herself and her children.

Translation -- this divorce ain't gonna come cheap.

Still, Pilar says she isn't 100% convinced the marriage is dead ... chalking up Deion's recent behavior to a "temporary lapse of judgment" ... and insisting she's "confident that he will come to his senses and return to his family as he has in the past."