So you were common-law anyways, even if you weren't married. Doesn't matter what country you lived together.
This means even if the whole Vegas marriage thing never even happened, you would have still committed misrepresentation by not declaring her as your common-law partner, and she still would have been banned forever to be sponsored. Would not have mattered if you later got married.
There is realistically no way you can ever sponsor her now. Two times over. Whether you get the marriage annulled or not is irrelevant as the damage was already done.
You have 2 options:
1. Have her apply for PR independently as skilled worker or something
2. Renounce your PR status, and start again from scratch this time properly declaring her in your app.
Those are your only options. Taking this through a sponsorship, rejection, appeals, etc will cost you tons of money in lawyer fees and take many years, only to end in rejection at the end.
Thank you for your comment.. so if I choose option 1 then I can keep my PR status but my wife has to apply her PR by her own. Is that right? If so then, what I need to do for my PR status? Report to CIC about this material changing?