In 2 weeks, when you go to Retrouvaille. In the meantime, keep up the no criticizing. That is the most important thing. Just keep getting along. It WILL work out at Retrouvaille. You have nothing to fear there.
This is the hardest time. You both will have a fear of Retrouvaille building inside of you. Don't let it shake your resolve. The most important thing is to just walk through their door. After that it will be easy. Retrouvaille will bring his focus onto you and the family. He will see that he needs to let her go. He'll make the decision himself. Just keep acting happy and nice, enjoy the family together. It will be really together soon.