I've read your previous posts talking to Unicorns&Rainbows and Sheogorath and know that you have thought about the values that should be in a relationship, and understand the factors that made your father walk away from your grandfather.
Here in this relationship you are always reacting, and your wife is taking the lead, and sadly falling through to bouts of toxic behavior. As you say the reason could be reason could be one of several thngs.
I guess in such circumstances you could try to continue going along with this, and evade the worst of it as best you can, not a hopeful prospect, you only have limited endurance to emotional battering, the same as anyone else. I doubt your daughter will benefit from this example of a partnership. Do you think doing that is viable long term?
Another alternative is to try to act reasonably, so at least you can regard yourself as worthy in your own right, provide a stable example to your daughter, and let your wife see you are not reacting to excess whilst maybe helping her realize what she is doing.
For me this would be to follow Tony's suggestion and seek counseling, at least for your self, with the door open should your wife ever desire to either join you or in some other way seek medical diagnosis and support. It may give you understanding of the problem and even strategies to deal with it and support your daughter.
As you have indicated this will probably not be well received, all I can suggest is that I would announce this during a 'quiet' period and emphasize I was doing it so as to remain together.
This of course is just me, I cannot make any real suggestions for you, as the person on the spot it is your judgment that counts.
What do you think?