No one will tell you to violate a court's order. You need to take your decree to a family lawyer near you for a consultation. You may ask for a modification to get child support, just because he threatens 50/50 does NOT mean it will happen. Get a consultation.
I am not intending this to be legal advice, because I don't know the particulars of your situation. Call me if you would like to discuss this or other isues.
You say in your question that you have an "agreement" on custody, but also that there is a court order. Until the order is modified (changed) by the court, all parties are legally obligated to follow it. If you feel as though circumstances have changed, you should consult with an attorney and consider going back to court. Gather your papers together and bring them with you, if you set up an appointment. Don't let his threats keep you from making a good decision for yourself and your daughter. Any good, local family attorney will be able to answer your questions and help you decide what to do. Best of luck to you.
This answer is for informational purposes only and does not establish the attorney-client relationship. You should always consult a local, experienced attorney for advice and help.
Again complete answers require much more information from you. First when was the decree (divorce or paternity entered?) A Family court always retains jurisdiction to consider modifications and no amount or type of agreement between the parties can divest the court of its authority to modify and award a appropriate child support. The Texas courts have consistently held that it is against public policy to attempt to prevent consideration of prospective child support based on the agreement of the parties. Rather, the bests interests of the child are paramount and will allays be considered. The child support amount is controlled by the provisions in the Texas Family Code section 154 and certain amounts are presumed to be proper minimums based on the proven income of the paying party. Zero is never considered an appropriate amount . Additionally, how much someone visits is not a basis not to pay. In fact I have argued that abandonment of visitation rights increase the obligations financially of the primary parent and should in itself constitute a basis for a higher level of support. Examples of the increased burden placed upon a primary parent would include more child care and emergency (last minute coverage for canceled visits). His failure to regularly visit can support even less visitation entitlement in the future . Again far more detailed consideration can only be made with far more information including what the exact terms of the Decree contain.