Wife Infidelity

I am a Muslim boy, who feel in love with a Hindu girl and got married to her in the year 2003, 1. First by Arya Samaj Hindu Marriage and gave an affidavit that I had converted and embarrassed Hindu religion, without changing my name. 2. Since we need to register over marriage, for passport and other reasons, so, the judge at Delhi Court asked us to marry according to Special Marriage Act which we did and registered. 3. Finally, to convince my parents my wife gave an affidavit in the court of law that she has changed her name and embarrassed Islam (gave adv. in local hindi news paper). And finally, got registered and got the Nikha Naama from the registered City Qazi Like this we got married. We used the same Nikha Nama to procure our respective passports and moved abroad and stayed their for 10 years. And had a son, who is now 10 years old. Me and wife were working in the same office and living happily apart from some minor family rifts because of my mother staying with us. Later in the year 2012 we moved back to India, as per my wife's wish and desire. After returning back I caught my wife having an extra material and physical relationship with one local person, because of which she wants to move away. But she continued her contacts with him after returning back to India. When, I searched her e-mail, I found out that she had physical relationship with that person and she feel in love with him, to an extent that she stayed in a hotel for one night by making an false excuse to me, and later he visited my house many a times to have sex with her in my absence. She confessed her infidelity later. (The details of how I caught her and the whole episode can be provided if required) Now, I am not able to digest this, in-spite of my efforts since last 3 years. The present status is am abroad on an official assignment. My mother is staying with my brother and my wife is in India living as housewife with my son at my brother's vacant house. Now, I want to have a divorce from her, but, have the following reservations for which I am seeking your advice 1. Will I get the custody of my son (he is 10 years of age) 2. Do, I need to give her the maintenance after divorce 3. Approximately, how much time the court will take to give us divorce 4. What document the court will accept as a proof for her infidelity.