What do you do if your future SIL is a controlling wacko nightmare?
And they just got engaged? Do you sit there awkwardly not congratulating them? Do you say something quietly to your brother alerting him to your fears? Do you talk about how dysfunctional they are to the rest of your family? Do you cry to your own partner in frustration? Do you write off your brother until or unless he comes to his senses? Do you stage an intervention with the rest of your family? Do you do nothing and cry inside?