First of all, if he’s legally married to you, he was ineligible to marry this other woman. This second marriage is invalid. Bigamy is illegal in Canada.
If he has indeed “married” another woman, you will need to prove that you were married first and never got divorced in order to invalidate this other marriage.
However, even if this other marriage is invalidated, it’s hard to see how your sponsorship would still go through, as your relationship is not genuine. Why hasn’t he withdrawn the sponsorship application?