Spouse left to India with child how to apply for the custody of child

I live in the US and my wife left to India taking my 2.5 year old daughter and said she will not return. This is 3rd time she is doing this in 6 year of marriage. I am thinking of Divorce but I would want my daughters custody and she is a US citizen. I have sent her an email asking her to let me know the status of the kid weekly. 1. What should I be doing to make sure if I file for divorce and file for kids custody that I do all the due diligence as a father to my kid when my spouse too the kid away from me. 2. My spouse does not work now so I am the only income producer for the family. I want to know what are the chances of me getting my daughters custody? If my spouse fights for the custody what kind of child support am i looking at if the court decides to have the kids grow with her mom? Appreciate your help in this regard.