It doesn't appear this is a divorce issue. This is probably more appropriately handled by an attorney that deals with real estate and property. Liens are complicated legal issues that the average pro per doesn't know how to handle. Please seek legal counsel.
The simplest way to handle this is to ask the lien holder to release the lien AS TO THE PROPERTY ONLY. And explain that it was wrongfully filed. That way it remains attached to your ex. If they fail to agree to do this contact a local attorney help you navigate this unfortunate situation.
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