If you want to quash the OP, you should first request a hearing. It will be up the filing party to demonstrate by a preponderance of the evidence that you have committed the actions alleged. OP's are generally freely given initial, but much harder to sustain at an evidentiary hearing. Bottom line, if the filing party cannot but forth evidence aside from their testimony demonstrating the alleged conduct, then the OP should be quashed.
You need to request a hearing immediately and make sure a copy of the request is filed with the clerk of the court that issued the order, and a copy of the request is delivered to the judge and mailed to your ex. You will then need to litigate the hearing and prove that the order should not remain in effect.