Still, the baseball star's relationship with the singer "was the last straw" before the Yankee slugger's wife filed for divorce Monday, her Houston attorney, Earle Lilly, tells PEOPLE.
Lilly says that A-Rod was smitten with Madonna, but makes no claim of any sexual liaison. "The correct analysis is a relationship," he says. "Some people categorize an affair as something as sexual infidelity. We're not claming that. It's an affair of the heart."
Over the weekend, Madonna issued a statement to PEOPLE denying a romantic relationship with the baseball star, saying, "I have nothing to do with the state of his marriage."
In fact, "Madonna's name is not even mentioned in the papers," says Lilly. "We don't want the public to think this is an aggressive action against Madonna."
Still, Lilly maintains that A-Rod has behaved badly for "a good while" and his client, Cynthia Rodriguez, has had enough. "She's just a Greek Orthodox lady who has had as much as she can take," he says.
Shortly before 9 a.m. Monday, Cynthia's Miami attorney Maurice Kutner filed the divorce petition.
"This is an action for dissolution of marriage, which is being filed only after [Cynthia Rodriguez] has exhausted every effort to salvage the marriage of the parties," the document reads. "However, Alex has emotionally abandoned his wife and children and has left her with no choice but to divorce him."
Without naming any names, the document states, "The marriage of the parties is irretrievably broken because of the husband's extramarital affairs and other marital misconduct."
The couple were married Nov. 2, 2002 in Dallas. They have two daughters, Natasha, 3, and Ella, 2 months.
Both Lilly and Kutner maintain that their client hopes to settle the divorce as amicably as possible.
"Cynthia has made it very clear to me that she wants to take the high road and protect her children and herself," Kutner said shortly after filing the papers. "She wants to resolve the issues between Alex and herself in an amicable fashion."
A lawyer reportedly representing Alex Rodriguez did not immediately return calls for comment.