+1(514) 937-9445 or Toll-free (Canada & US) +1 (888) 947-9445
I would report him to the RCMP or something similar. Maybe even contact CBC. They recently did an investigative report on this situation and could help advocate for you:
https://www.cbc.ca/news/canada/polygamy-canadian-muslim-community-1.4971971

Note that while he can get in legal trouble in Canada, he will not lose his citizenship if he already was a Canadian citizen when he married you.
Agreed. There is a specific part of the bigamy law that deals with this situation. A criminal offence has been committed.
https://laws-lois.justice.gc.ca/eng/acts/C-46/section-290.html

Bigamy

  • 290 (1) Every one commits bigamy who
    • (a) in Canada,
      • (i) being married, goes through a form of marriage with another person,

      • (ii) knowing that another person is married, goes through a form of marriage with that person, or

      • (iii) on the same day or simultaneously, goes through a form of marriage with more than one person; or
    • (b) being a Canadian citizen resident in Canada leaves Canada with intent to do anything mentioned in subparagraphs (a)(i) to (iii) and, pursuant thereto, does outside Canada anything mentioned in those subparagraphs in circumstances mentioned therein.
 
Hi. I need your help to guide me. My husband is a canadian citizen and fraduently married me last year in January in pakistan showing himself a divorced man. He did not register our marriage in pakistan and later i got to know that he is already married in Canada. I have filed for divorce on the basis of pictures and video that I have of our marriage as a proof. Now I want to take a legal action against him and want to report a fraud against him that he has committed polygamy which is a crime under canadian law. Also, he is also harrassing me not to report to his fraud in canada. Can u please guide me the process and also what will the possible outcomes of this issue especially on his citizenship status?
Report this directly to the RCMP in Canada. This is a criminal offence and nothing to do with immigration.
Criminal Code - Section 290(1)(b).
 
Whatever you want to do, will be more effective if you are in Canada and yes it won't be cheap. You can also try getting help for women right activists like https://www.canadianwomen.org/