If you need any assistance for wiretapping your home, you can use products from this site https://www.brickhousesecurity.com/ . I can offer some offline guidance in how to tap phone, emails, etc but you need to be cock sure of the local laws of Dubai before you actually implement it.
Without analysing the situation any further, I think the posts above have more value than a hired attorney could provide.
Here are my thoughts on the projected situation.
1. Continue goodwill by exploring peaceful discussions. I would add that you reach out to a Family and Marriage Therapist or a Psychologist. This will cover you big time and wont be your word against hers. Maintain an online diary with your good will activities and also minute details of her abberations.
2. Protect yourself.
(a) On the lines of Tajs advice, file for protection of life/limb. I have posted a draft letter which you can improve ( its a google doc )
(b) Collect evidence. Phone, Web , email , sms all put together should provide you enough evidence.
(c) Dont make haste/become type A. No law will support you or beleive you if you slap a women and admit that you did. I am not a lawyer but from my reading of S. 81 of IPC, you cant cover yourself using this authority as you state that " you slapped her twice as she crossed her limits. The following two illustrations may help you appreciate your situation in the context of S 81. Your situation is no where close, IMHO that can afford protection under this section, unless you can say/prove that " you slapped her twice to protect your son being raped or you slapped her twice to prevent outrageous conduct of exposing herself to the neighbor on so and so date witnessed by so and so..." on those lines.
(a) A, the captain of a steam vessel, suddenly and without any fault or negligence on his part, finds himself in such a position that, before he can stop his vessel, he must inevitably run down a boat B, with twenty or thirty passengers on board, unless he changes the course of his vessel, and that, by changing his course, he must incur risk of running down a boat C with only two passengers on board, which he may possibly clear. Here, if A alters his course without any intention to run down the boat C and in good faith for the purpose of avoiding the danger to the passengers in the boat B, he is not guilty of an offence, though he may run down the boat C by doing an act which he knew was likely to cause that effect, if it be found as a matter of fact that the danger which he intended to avoid was such as to excuse him in incurring the risk of running down the boat C. ( Nandha cannot be A ! Nandha cannot prove good faith. )
(b) A, in great fire, pulls down houses in order to prevent the conflagration from spreading. He does this with the intention in good faith of saving human life or property. Here, if it be found that the harm to be prevented was of such a nature and so imminent as to excuse A's act. A is not guilty of the offence. ( Nandha cannot be A ! )
3. You have not mentioned anything about how she is handling the responsibility of mother and parenting. Is she a good mother and parent. Pile up evidence on her poor parenting skills, child abuse.
4.If she is a good mother, then try to see the big picture. There may be other psychological issues - post partum depression or other issues that may be playing a role in her behaviour. Also, when one is away in a foriegn country, locked up inside the 4 walls of an apartment, one may get frustrated with the responsibilities and demands a 4 month child may impose on a young mother. She needs a break too. You may be going to office, getting to interact with other humans, get fresh air outside the home. She does not get the breaks and is tied down with the baby. Try to get some help from your or her family during the trying times of early child rearing. Send her to India for some time to her family. It may give her a lease of life. Then try to visit her in favorable situation. If she is a educated women, then she may have aspirations of working and having a career. Discuss those things and see if the underlying frustration is due to her inability to work. I , for one fully support women working.
When my wife was pregnent, I invited both her parents to US and tried to make their life as comfortable as possible. Of course, there were issues due to post partum but the presence of her parents was a big shock absorber.
While it may appear that I am sympathetic to you on this forum, if I were the girls party, given that you slapped her twice, I would have put you behind bars by now, filed 498a and made your life miserable in Dubai and India. I would not mind being slapped by my wife who is taking care of my 4 month old. Two slaps is minor pain compared to what she has gone thro bearing your first child.
Monitor the situation continuously and keep smiling - dont show that you are perturbed. You state that her brother is a goon. In a country of a billion, if her brother got any of your family members "eliminated", what can you really do ? File a motion for protection. Law is for those who fear or respect laws.