It doesn't sound like 產後depression, but medication definately will help. Treatment is an good option before filing divorce as my opinion.
In the city where I used to live, there is a "mobile unit" that compose of social workers and psych hospital staffs. I got their number from cops. I call them when my wife was on a episode and really disturbing neibours, or had tendancy to harm herself or other people. Those social workers will come, determine the severity, and can put her into psychi hospital again her will.
She started treatment this way. Her symptomes wax and wane. It is difficult to keep her medicated. Somehow with family members help, her situation is now under control.
Your wife's psychi problems seems to be paranoid. It can be simply a kind of personality disorder, or a brief psychosis, or indicative of more severe diseases like mania or schizophenia paranoid type. In general, if the onset is early, like before 30s, has other symptoms like hallucination, and if she cannot take care of herself and loss the social function also, then the prognosis is bad. On the other hand, if the onset has an obvious stressor, like she got the disease after her mother died, then the prognosis might be better. Anyway, I think she need to see a good psychiatric doctor, for the sake of treatment, and the documentation of her disease for the future divorce if you finally choose to file.
I will say getting legal info from a divorce lawyer or marriage consultant. I will say if you file divorce based on her mental status, it is unlikely that she can take care of children after divorce.