Alimony in divorce case

Sir, I have married to my wife in 2015 after a love affair of 3 years, but haven't done registry. After that she wants and live for most of the days in her matrimonial home. In January,2020 I have got the real cause of her distraction, I found some sms in her mobile, she communicated to her boyfriend like "love you, We are going to be married" and also found a photo with the person. When I asked her about those, she became arrogant and started blaming my mother and my sister and left my home. After that she started threatening me to file 498a against me and my family that we have drive her out from my home. I tried to calm her but she want to live separately with me, which I can't. After the incident I have been sending money to her for each and every month by IMO, also sending medicine, dresses and her daily essentials by courier. Now she is trying to get divorce and wants more money as alimony. And if I am not willing to give her divorce, she threatens to file 498a and DV case against me. I have a gross monthly income of Rs. 49000/- and I have loan EMI of Rs. 22000/- and thus net salary after all deduction is 25000/-. My wife is not earning and a post graduate. Now my question is that- 1. Can she file 498a and DV case against me? 2. How much alimony I have to give if she wants divorce?