If they suggest that you did not meet the residency requirements at the port of entry and that is not even certain as it is possible that they will just let you walk through, you can tell them that you had a good reason because of family problems and they will probably let you through without reporting. If they go ahead with reporting you, they will still let you enter Canada but they will give you some papers and tell you that if you want to appeal for your PR, you must do it within 30 days. You would then appeal to keep your PR based on not being able to meet the residency requirements due to family problems. I have no idea what the odds are of winning such an appeal if it comes to that.