After you file


@Diamondpr wrote:

Our divorce was finalized in 2018, I never signed a 8332 form. 


In that case, your ex can claim nothing unless you give your ex a signed form 8332; your ex can't claim the dependent using a copy of the divorce decree.

 

However, if you refuse to sign the form 8332, you will be violating the court order, and if your ex takes you to court, the consequences could be grave.  Don't ignore or violate a court order without qualified legal advice.