If this means it takes 90 days to get divorced, then you should know that if you went this route:
* file for divorce
* bring divorce filing to I-751 interview
* request at interview to amend to a divorce waiver
then the published USCIS procedure is to issue an RFE, and give you 87 days from the date of the RFE to produce a final divorce decree.
The timing is tight, but given your I-751 interview is in 2 weeks, if you have the divorce filing in hand, I would want to get the immigration nightmare behind me as soon as possible.
IME (state of Colorado), it takes less than a week for a lawyer to file for divorce, which (in Colorado), requires the other spouse to be served with the notice or acknowledge receipt of the notice.
Get a divorce lawyer and see if you can file before the I-751 interview.
Otherwise, yes, re-schedule the interview to buy time (alas it could buying years). Then amend once the decree is in hand, or at the interview if it happens before the decree.
Withdrawing N-400 is not your priority now. Meeting a divorce attorney is.
87 days per https://www.aila.org/File/DownloadEmbeddedFile/47718