Other people's experiences with their daughters in law are not LadySu's. The daughter in law is not wrong for her reaction to someone making her unborn born child's potential death about her. She is not a narcissist because she is struggling to forgive LadySu, who seems without remorse based on her own minimizing and denials of wrongdoing across various posts. No evidence whatsoever that the daughter in law is coercively controlling her husband who is expressing his own rage. She is distancing from toxic behavior, as she should. The daughter in law is not wrong here. The son is not wrong for not bringing the OP into his home with this disruptive behavior. He is 10000% correct to protect his wife from this drama.
What about my own experiences? My own experience with a mother in law who behaved similarly to LadySu lead to my husband not wanting to continue a relationship with her. He was not abused, coerced, or forced to choose by me between his mother and his wife. He chose peace and the family he created as a result of his mother continually pushing and debating our reasonable boundaries. OP's son's boundaries are reasonable. It's disrespectful to keep telling him he is wrong simply because she doesn't like the boundaries.
The Op's son hasn't cut her off yet. I do not see positive, kind, or benevolent intent in trying to convince LadySu that her daughter in law is a malevolent person with mental health issues. For sure, if she behaves as though the daughter in law is the source of her problems, the son will not want to see her. Why would anyone with a healthy sense of family relationships want to drive that idea into LadydySu's head? I see no positive intent in comparing the daughter in law to anyone's "allegedly" narcissistic daughter in law. NPD is a medical diagnosis that no one here is qualified to give this poor woman going through a rough pregnancy.
What you did or didn't miss isn't my concern Smileless. I paraphrased the OP's general attitude toward her son and daughter in law. I'm sorry if you struggle to discern what you should and shouldn't take literally, but that's not my problem. I feel your posts about her daughter in law and your "diagnoses" are wholly fanciful, bitter, and not applicable to the situation. You and I don't have to agree. I am not trying to convince you of anything at all. My comments are toward the OP because her behavior and thought process resembles much of my own mother in law, a woman whose children prefer distance. I am trying to help her see the other side of the coin in hopes of her not ending up like my mother in law. Only God knows the intentions of those trying to convince her that her daughter in law is the problem. However, you and others like you are free to comment as you please. As am I.