1. She filed RCR and now not coming back? Awesome! Run to a lawyer, you are in great luck. File a divorce on basis of willful desertion, as she was the one who filed RCR and now not coming back.
2. If your son's age is less than 5years old, wait for him to be atleast 6 and then apply for custody of child, if you want it. You will be granted custody since you are working and your wife is not. Don't fight for child before 5, it's no use. Court generally gives custody of child less than 5years to mother and visitation to father.
3. No maintenance is awarded to wife if she willfully does not want to live with husband. She filed RCR, you said you want to live with her and then she declined. You are at an advantage here.