There is no such rule that CIC can take your PR status back after getting it on spousal basis if your application was right. That's why they are too much alert when they have to give the visa. So, don't worry and live boldly. Some mistakes can happen, but she had already given the correct date. Maximum you can do is, just give assurance to your ex-wife that you will not take any social assistance from government. Well, even if you ask that, govt will charge it to your ex-wife. But as a good human being, just don't give any trouble to her, and if possible, just leave the city and start your new life somewhere in Canada where she can not reach you. Otherwise, legally she can not do anything to send you back.