When your spouse files a Petition for Divorce from you, your spouse is basically notifying the Court that he/she wants a divorce from you. The petition spells out who the parties are, where process should be served, the date of marriage, the date of separation, the grounds for the divorce, the children of the marriage (if any), and how the community property and separate property should be awarded in the divorce. A counterpetition is simply a counterclaim against the person who filed a petition against you. In a divorce, you file a counterpetition to let the Court know that you also want a divorce from your spouse.
You can list any and all additional issues in your counterpetition for divorce that you believe the Court should be aware of. For example, you could allege an additional ground for divorce such as adultery if you want to pursue adultery as a reason you should be granted a divorce on top of the usual ground of insupportability.
As a practical matter, one of the main reasons to file a Counterpetition for Divorce is to eliminate the possibility that your spouse could suddenly change his/her mind before the divorce is finalized and dismiss the divorce case unilaterally. Under Texas law, when you sue someone for anything (including a divorce), you have an absolute right to unilaterally dismiss the petition. This is called a nonsuit. The case simply goes away.
However, if the Respondent has filed a Counterpetition for Divorce, the Petitioner cannot unilaterally dismiss the divorce. Suppose a wife files a Petition for Divorce and later changes her mind about going through with the divorce. If no counterpetition has been filed, then the wife can file a Notice of Nonsuit and the divorce case quickly goes away without a hearing. If a counterpetition has been filed, then she cannot dismiss the divorce case without getting her husband's consent to do so. (The wife cannot dismiss the husband's counterclaims, that would be up to the husband and his attorney.) If the divorce case goes away, then either party can simply pay another filing fee and wait another 60 day waiting period and pursue the divorce for a second time.
As a side note, I encourage couples who are going through a divorce to reconcile if they can do so. Many times over the years I have had someone ask me to dismiss their divorce petition after they have paid the $300 filing fee to start the divorce process. I will encourage them to try to reconcile, but I also recommend that we not dismiss the divorce petition right away. That way they will not have to pay another $300 filing fee to start the divorce process all over again if the reconciliation does not work out. If the reconciliation is working and if the divorce petition is still pending after a year or so and nothing is happening in the divorce, then the Court will send a notice that the case is on a "Dismissal for Want of Prosecution" docket and you will have to deal with the possibility of a dismissal then.
The filing fee to file a counterpetition is currently about $75. If you have been sued for divorce and you also want a divorce from your spouse, you will want to consider filing a counterpetition for divorce in order to avoid the possibility of your spouse dismissing the divorce case before a divorce is granted.
If you have any questions about filing a counterpetition for divorce, call Ken Crain at 512-869-0131.