Even though I'm the one who discovered this Pandora's Box, I want to say that this
Quote: I will first ask her whether she has thought about what I told her about co-sleeping in Japan leading to wide-spread child abuse
doesn't seem like a very productive way to bring up the subject. Clearly co-sleeping is very common in Japan, whether or not there is widespread child abuse. Clearly, your wife sees nothing wrong with co-sleeping, and I suggest that if you bring it up in a way that challenges not only her cultural norm, but her opinion of the practice (and you already know her opinion), she'll get defensive immediately and the walls will go up.
When you said that your daughter said that she gets nightmares when she sleeps alone and this almost made your wife cry, that makes me think that it reminds your wife of when she was a child. It struck a chord with her.
You might get farther if you approach the subject in a more oblique and diplomatic way. You could start with something like, "I've been thinking about the co-sleeping arrangement, and there are some nice things about it. It's very cozy and sweet and it must make the children feel very safe and protected. My parents and I never did this, but I'm wondering what it was like for you? Was it a pleasant experience? Did it make you feel safe and loved?"
This opens the door (which I doubt if she will walk through) of her reacting, "Oh yes, I had terrible nightmares if I slept alone. I was scared to sleep alone."
Or more waffle-y, "Well, everyone did it. It wouldn't have occurred to me to sleep alone, and anyway, if I had wanted to, my mom/uncle/father/grandfather wouldn't have allowed it."
Or something unexpected like, "It was my mother/uncle/grandfather who had nightmares if I didn't sleep with him/her. I wouldn't have minded sleeping alone."
Or, "We all slept together unless we were being punished for something. Then we had to sleep alone and it was awful until mama forgave us."
Who knows what went on back then? You said once that she won't talk about it.
In any case, bringing up the topic in a kinder, gentler way shows that you understand that this is a value for her, and that you are not challenging her belief that this is a good practice. It seems to me that the way things are right now, she sees you as an adversary. She feels that she has to defend her beliefs and her practices.
If-- and it's only an "IF"-- she was abused as a child, it would be very hard for her to admit it to you if she doesn't feel safe. In her culture, it's possible that whatever went on-- and again, it's only an IF-- was considered the norm, and to complain about it would put you outside the pale. I know enougn about Japanese culture to know that the group is generally valued over the individual, and that if that group is the family, it is valued over all.
Even rebellious, independent American girls have a hard time acknowledging and sometimes even remembering abuse... I would imagine it would be even more difficult fof a Japanese girl/woman.
Edited to add: I just read on the other thread that your wife initiated your first sexual encounter. That's really interesting... was she really interested in sex early in the R? Sometimes abuse victims can be VERY sexual... even promiscuous. As a flight attendant, does she have guys coming on to her a lot?
