I totally agree with adv. bharat chugh. Your question of ex-parte divorce requires further clarification and hence, I venture for this:
For getting ex-parte decree, the divorce petition has tobe properly served and the respondent having full knowledge of the case, does not show up in the court to contest the case, then only the court grants ex-parte divorce. If you mention in your petition the address of the husband (which is known to you on the basis of the marriage certificate and also you fully aware that he is not presently residing there), the notice come back with a remark that respondent does not live there. In such conditions, the court will again direct you to file a fresh address. If the court is satisfied that the respondent is intentionally avoiding the service, then only direct you for paper publication. So, I suggest you to find out his official and residential address by engaging a detective and then proceed for divorce case.
I am sorry to say this, you also find difficulty to find a ground for divorce. Even though it appears on the face of it, it is desertion, but in strict interpreation of the term of desertion, your willful separation does not fit into the definition of desertion and cruelty ground is also not available on the basis of the facts you tried to express.
Finally, the divorce case can be filed at the place where marriage was solemnized (means Delhi) or the place where the parties resided together (it does not applicable) or where the respondent is residing at present (you do not know this place) or the place where you reside at the time of filing the petition. Delhi has got definite jurisdiction to file the case. You can also file the case, where you are at present residing.
Ex-parte order can be set aside within 30 days of the passing of the order or within 30 days of the having knowledge of the passing of the order, subject to the respondent's ability to satisfy the court why he could not contest the case. He can also file the appeal within 90 days in the High Court. The general trend is that in matrimonial matters, if ex-parte divorce is granted and the party got married to another person, and if the court satisfies that there was no fraud in obtaining ex-parte divorce, the courts will not set aside the ex-parte divorce decree and do not disturb the second marriage.