Maybe not saying anything prevented some type of scene, considering what they are like.
I know it must be terribly difficult to look at the woman who once your loving W and wonder what has happened. The very shock, alone, is enough to knock a man off his feet.
Some women act the way you've described as a means to get clear message to the H. Her mistreatment is partly due to her resentment, as well as any other WW attributes. Some women act this way in order to discourage the man from trying to get closer, talk, change her mind, etc.
MIL wanted to be a shield for your W. Based on their past R, it won't be long until they'll blow up again.
So sorry for those 3 little girls.
It is not about what you feel should work in your M. It is about doing the work that gets the right results. Do what works!