Don't withdraw anything. I pointed out that you need to do. Re-read my post.
I don't think you'll be able to get a final divorce decree in time to reply to USCIS. Hence why I edited and explained that respond with the papers from the court that says you filed divorce.
As soon as you get that final divorce certificate, send it with a copy of your I-751 receipt notice to the address at the bottom of the receipt notice.
I see for VA, you're eligible to file divorce after 6 - 12 months of separation (depending on circumstances). Well, you've exceeded that. So, file that divorce today and get it rolling.
In the meantime, if you have 60 days or so to respond to RFE, then I believe you can just wait to get final divorce. However, if you don't have much time/ anticipating a fight with ex-hubby, then resort to paragraph 2 above.