Desertion

what is the status of the divorce petition she filed? 

Your wife left you in 1996 and then in 2009 she filed a divorce case? What were you doing during these 13-14 years? BOSS, if husband and wife does not stay together for 7+ years then they are automatically divorced. 

So chill out and find another mom for your kids. 

On what grounds she have filed divorce? That letter is one of the evidence. All depends upon other evidence also. 

Your children are better witnesses for desertion than the letter though letter also has its value to prove her adulterous behavior (not adultery).  Desertion as a ground is sufficient to get divorce. Filing for divorce and petition after 13 years itself makes her petition groundless. Adulterous behavior and tendency to indulge in marriage with a married person while she herself is your wife is bigamy.  This is help you to fight her maintenance claim.  Evidences taken under Family courts act are not strictly put to test as it happens in Indian Evidence Act. So letter helps, you may seek the help of graphologist/handwriting expert to compare her handwriting with the handwriting in the letter to prove it belongs to her. 

the divorce petition is in the evidence stage.My lawyer is now questioning her.

Mr.Arjun Gupti in which clause does it state that not living together for 7 years leads to automatic divorce?