I've decided to include a cover letter to USCIS explaining my case:
Dear Sir/Madam,
I am filing for my I-751 application, Petition to Remove Conditions on Residence. My ex-wife and I are currently going through divorce proceedings, and the divorce has yet to be finalized. As a result, I do not have the final Divorce Decree with me to include in my application. However, I have attached proof of our divorce mediation and agreement that was drafted by my ex-wife’s lawyer for your verification.
I am also still in the process of collecting further evidence of our bonafide marriage. My ex-wife was the one who handled all our paperwork, and we are no longer communicating with each other. This is why I was not able to include all of the evidence and supporting documents of our marriage in my application. I will have all of the evidence and paperwork for our marriage ready in the near future.
Thank you in advance for your time and consideration.
Respectfully Yours,
(signature)
What do you guys think?