Someone out of state who is having an affair with my spouse got an order of protection based on lies. What can I do?

Unfortunately, you'll have to contest the petition for order of protection. Once you get the petition for order of protection dismissed, you can sue the person who filed it in the same case for all the expenses you incurred defending yourself. 

“Untrue statements. Allegations and denials, made without reasonable cause and found to be untrue, shall subject the party pleading them to the payment of reasonable expenses actually incurred by the other party by reason of the untrue pleading, together with a reasonable attorney’s fee, to be summarily taxed by the court upon motion made within 30 days of the judgment or dismissal, as provided in Supreme Court Rule 137.” 750 ILCS 60/266

If the court didn't issue the petition for order of protection, it must have found the allegations contained therein to be untrue. Therefore, the court "SHALL subject the party pleading them to the payment of reasonable expenses actually incurred."

I am sorry you went through this. 

you can challenge his OP or file a petition for a cross OP.