Moving Out-of-State with Child

How can I go about moving my son and I to Texas? He was born there, as was I. I have nearly full custody of my son; my ex has 36 hours per month with him, in addition to holidays. The rest of the time he is with me. I have no family here, no support other than her family – who are all hostile to me. It is well known that being a single parent is hard at best, but in my situation, it is more so. I have family in Texas who can help, plus the numerous other reasons I have for moving. Yet, the documents I have say my son can not leave the state without consent or a court order. She will not consent, and has told me that she will probably lose in court, but will fight me anyway. I just want a better, more peaceful environment in which to raise my boy. What do I need to do in order to get that court order?