I filed 751 with divorce waiver. Approved with no interview. That was more than 3 years ago, but I can't imagine a case not being approved if you filed it correctly with an abundance of evidence of bona fide with no fraud flags.
I think there's another hurdle here to consider in your case. Currently you are joint and it sounds like the divorce process hasn't started.
Some places require a minimum separation time before being able to file with the court. (++ Time)
The court process itself can take time because you need to properly serve the notice of court filling to the other party, make sure all your forms required by your jurisdiction are completed, etc before a clerk will put your pleading on the judge's desk to sign. (+++ Time)
Above also assumes your ex will not contest it in the court and/or there won't be items the court needs to hammer out between you like assets, children, etc..(+++ time)
All while the divorce is happening and you didn't notify USCIS, USCIS might not interview you thinking all the evidence you submitted is good to go and that you're still joint.
Later if and when you apply to be a citizen, your entire immigration history will be up for review. You will run in to trouble here when the circumstances of your 751 is reviewed. You might get denied, wasting all that time and money.
In short, work out your marriage if you can. If you can't, get a move on with the divorce for your own sake.