Upgrade to immediate relative based on approved vawa

[Fehervirag]

I just found out that my ex husband is a registered voter in my states which implies that he received his citizenship. Based on the laws, what I read on the USCIS website, if he receives his citizenship my case also should be upgraded to the immediate relative category even after the divorce.
Now I wonder how to proceed. Is anybody done this before? Do I have to notify the Vermont Service Center where my original application went or the local office? Is there a specific letter to send?
Any input would be great.