My X moved out of state and stopped paying. How far behind does he need to be before I turn him in?

You can file a petition (that each state treats with "full faith and credit" of Contempt of Support Order against your ex. (Your current husband is not responsible for supporting the children of the previous husband -- even though I'm certain that he has tried to help you out because he loves the children too.) And you should not wait to file that petition. Because he's in another state it will take much longer for the Contempt Petition to be heard in the court. First it will have to be processed in your court of jurisdiction and then it will be sent to the reciprocal court in TX where they will "haul him in" and it may be determined that his wages will be attached -- pursuant to Federal requirement -- and then the money for the current order (as well as something on the arrears) will be sent to the court and then then court will send you a check in the full amount. But you have to file the contempt petition and ask that his wages be attached before any of this process happens. Be ProActive in your case .. no one else can do it for you. Do it for your kids.