This is indeed a tricky situation. How do you know that the documents are fake ? Did you take part in making these fake documents and now that she has threatened to divorce you, you want to bring this up ? If that is the case and IRCC knows that you were a part in misrepresentation then you will definitely have a problem. Otherwise if you can prove in a court / arbitrator that you had no part in the misrepresentation whatsoever, maybe you can get your and your kids PR status unaffected. I suggest meeting a good immigration lawyer for this
