Cancellation.

[canadianwoman]

Unfortunately, CIC tries to be culturally sensitive, so the one time it might possibly be considered normal to answer 'I don't know' to questions about your spouse would be when the marriage was arranged. After all, they have only known each other for a short time.
Plus the OP is the one sponsoring, and so she would not be at any interview anyway (if it is an outland app).
If it is inland, then the sponsor would be at the interview. At that point answering 'I don't know' might work, though by then the two would have been living together for a while.

How about a 'poison pen' letter? CIC actually pays attention to them, though prefer them to be signed. But the OP could write an anonymous one to the visa office processing the file stating that she knows the couple in question well, knows the man is just in it for a PR visa, and that the woman is deeply unhappy and wants to get divorced.

 

[zardoz]

Sorry for the confusion. I meant spousal sponsorship, hes my spouse but i wanted to cancel it, but do not want them finding out I cancelled it because its going to cause problems for me,
i wanted to know if immigration will just tell them it has been denied or rejected instead of saying its been cancelled.
Thanks for your help

If this was an arranged marriage with the purpose of assisting someone to immigrate to Canada, it will be considered as a "marriage of convenience". If this is the case, it's possible that it might put you at risk as well.

You should, if you are no longer WILLING to be a party to this sponsorship, immediately notify CIC of the facts and withdraw the application. If it's allowed to continue, you are stuck with the possible financial consequences for at least 3 years and possibly much, much longer. You do realise just how the sponsorship undertaking works?