In Philippines we are living together since 2008 to 2011 before I came here. And then I had vacation last 2013 for 1 month And vacation again last 2015 for 7 weeks. The year when we got married. And he landed last April 2017. We are living together for 2 months last year.
Your allegation is weak for following reasons-
1) Your total cohabitation -
Before PR in Philippines - Around 3 year 3 months
After PR in Canada - 2 Months
2) You know the person since 2008 and you were in a conjugal relationship for a long time. Although you were living in Canada since 2011 but your 2013 and 2015 vacation proves that you have a steady relationship with your husband.
3) It is more logical that you can not be cheated by someone whom you know almost 9 years.
It is possible that your actual relationship might gradually t broke down slowly after you came to Canada. Your sponsored spouse might involved in another relationship but used your previous relationship to gain Canadian PR and that's why he broke up with you just after landing. If this is the case then you might have a chance.
But there is also a second thought of your story-
You and your husband might willingly conduct a "Marriage of Convenience" in order to facilitate your fake husband's PR in first phase and later in the second phase your fake husband will bring his biological child and the mother of that biological child. Something like "Chain Migration". It is very hard to believe that you know a person for 9 years but you did not know that he had a child or he had a relationship with the biological mother of his biological child. May be your fake husband did not mention her child in his PR application because he did not want to put his PR application in jeopardy. Now your husband is divorcing you and going to marry the biological mother of his biological child and bringing both in Canada.