I am not a lawyer, but can say that that sounds like bad information.
Firstly, how you you apply to sponsor her as your common-law partner if you are not living together. That question is moot, because you've already disclosed that you were living together for 6 years and you did NOT disclose that in your own PR application.
Suggest you find a `different' lawyer and make sure you tell them the whole story!
You don’t have to be currently living together to file as common law. You have to prove that you are still in a relationship and that you have lived together in the past for over a year to apply for sponsorship based on being common law. The fact they have been common law but did not declare it on previous application will now the big issue.