I was afraid that was going to be your answer.
You have a very big problem on your hands.
First of all, because you lived with your boyfriend for a year - you became common law. This means you no longer qualified to immigrate to Canada through your mother. Since you said you were single and didn't declare your common law status - this means you committed misrepresentation and obtained your PR status fraudulently. If CIC ever finds out about this - it's quite possible your PR status will be revoked and you will be ordered to leave Canada.
What this also means is that you can never sponsor your boyfriend. Even if you get married, you can still never sponsor him. If you try, this will draw attention to the fact that you obtain your PR status through misrepresentation. CIC will end up refusing your boyfriend's sponsorship application and quite possibly revoking your PR status.
The only option now is for your boyfriend to get PR status on his own (e.g. through Express Entry). Again, you can never sponsor him. If you try, he will be refused and you will likely lose your PR status too.