Firstly, there is no escape route for a husband and a biological father from giving maintenance. As you have stated that your wife has already taken divorce by way of exparte, there is a new law that has come up that even after divorce if the wife is not living on adultery and/or has not remarried then the wife can seek for maintenance once again but such needs to be proved then only. Hope you have a good lawyer to deal your case technically. Moreso after the ages of 7 or 8 years children are being asked by court with whom they want to reside, the father or mother, on that basis court grants and you can obtain your childrens custody.