If you have been served with a petition for divorce in Texas, you must file a written answer to the petition or risk a default judgment being entered against you. You may also wish to consider filing a counter suit, properly known as a counterclaim.
While an answer to a Texas divorce petition allows you to address the allegations made in the plaintiff's petition, it does not allow you to make your own allegations or ask for your own relief. A counterclaim, on the other hand, will allow you to make allegations and ask for specific things you want from the divorce.
Grounds for Divorce
In Texas, a divorce may be filed as a no-fault divorce or grounds for the divorce may be alleged. If you wish to allege your own grounds for the divorce, then you must file a counterclaim and allege those grounds in the counterclaim.
Spousal Support and Other Issues
If you want the court to award you spousal support or other specific relief you may seek in your divorce then you must ask for it in a counterclaim. If the issue was not addressed in your souse's petition then it is not considered to be before the court. For the court to consider ruling in your favor on an issue, you must first make it an issue in the divorce.