Marriage is a contract and that contract can be terminated by either party. In layman's terms, if either spouse wants a divorce, he or she can get one. The other party can't stop it.
If you don't want to get a divorce, but your spouse does, then non-legal options such as marriage counseling may be your best option.
On the other hand, if you and your spouse both decide to stop the divorce proceedings, you'll need to "Nonsuit it." That means that the person who filed the Original Petition for Divorce will need to file a Motion to Nonsuit.
You could also just wait for the court to dismiss the case due to inactivity, but it's probably not wise to leave an active lawsuit open if you've decided not to pursue it.