Best luck to you!

Have you collected all your evidence such as all sorts of contact letters from USCIS, FBI and other government agencies? If yes, I don't think you have to send such a letter to USCIS. 90% probably useless.
Please update with us about your case progress. Are you gonna file Pro Se or through a lawyer? I've already finished writing the petition letter and have most of the evidence. But I need to wait for the PD. Mine has been stuck on NC for over two years now.
Best luck to you!