THe purpose of service of citation is to give you notice of the fact that you have been sued, in your situation for child support and child custody, commonly known as a SAPCR. Service is a due process right that is neccesarily for a lawsuit to commence, but also is waivable with the election by the Respondent/Defendant.
Generally, if the respondent/defendant is in agreement with all terms and condition proposed by the Petitioner, than the respondent can sign a waiver of service and sign the final order that will be signed by the judge.
If you are in agreement to all terms and condition that your ex spouse is proposing, than you can sign off on the document that will be signed by the court. The reason why you were served may be due to several factors that has not been identified. It could be because she is doing this pro se and didn't know that you could of signed the waiver of service which would have saved her money in paying the process server. It could be because she proposed the child support amount and the child custody matter that you disagreed with, which would have required her to serve you, if you didn't agree to sign.
Sorry for the vague answer and hypotethicals, but more facts are needed.
if you are truely in agreement with your ex spouse about hte amount of child support and the child custody matter, than, consult with your wife and get the order signed. If not, consult a local family law attorney to assist you to representing your rights under the Texas family code.
Good luck and wish you success
Min Gyu Kim (Peter)
The statement above is general in nature and does not constitute legal advice, and in no way be interpreted as legal advice. Consult with a local attorney in your area to receive an answer specific to your case. This information does not create an attorney-client relationship.