I apologize for a delayed response. Sometimes I am just so swamped with work during the day that I cannot even find time to come here, even though I know it is super important for me to listen/understand/follow your advices.
"During your naturalization process, did you mention divorce to USCIS / CIS?"
Of course. 100%. And all the work regarding the naturalization was done by an attorney. A good one.
"Also, you said earlier the cert should have said single, but you were divorced. Those are different things"
At the time I was creating the OP I did not know it was such a multiple choice: for most purposes in this country it is either you're married or single. So I thought Single would the status (but "Widowed" is just total bogus: my attorney couldn't have put it on the application). Even if they would've put Single on the CoN instead of "Widowed" it would've been so much better. ...
And also: I want to thank each and every one of you for your attention to this case and thoughtful advices.
According to what I got from the advices, I will not be giving up on this K-1 and will continue the struggle till the end. And only then, if my fiance is still not with me, we'll be going towards CR-1. And, in turn, IR-1. I've talked to my fiance, and we're determined to fight for our relationship and this case.
And I understand that the most important thing now is correcting the error on the CoN first and foremost. This was perfectly explained.
Now, with that additional information that I have given (that many people were asking, as to how I got my N400), I hope to hear the advices based on those details: how my circumstances change for this case in that context. So, please tell me.