Advice for divorce

I am living in North Caroline. I am working, and my wife is a fulltime student. We have one 6 years old son. We are having unreconcilable difference for a while, major are the relation between two families.

In the worst case if divorce get into the picture, what I should do to get the custody of the boy and minimize the cost. I am reaching the point that I do not want to pay her a penny for the way she treat my parent.

Thanks.