Hello I believe I can help you with your concern. I am sorry that your wife is exhibiting this type of behavior, I can understand why you are concerned. You mentioned that you and your wife have had problems for years, but when exactly did you first begin to notice these symptoms that your wife believes everyone is trying to conspire against her? Also are there any other symptoms that you believe she exhibits that would be important to know about?
From the symptoms you described right now, I am leaning towards a diagnosis of Delusional Disorder Persecutory Type. This is a serious diagnosis because your wife believes other people are conspiring against her in some way, which leads her to not trust and not like others. One of the reasons she only gives you general and superficial answers is because of she is does not fully trust you, in fact she believes you are one of the conspirators, so she will not give you full detailed answers to your questions. The aggressive and violent reactions that you mentioned are a sign of escalation by her and are common with someone being diagnosed with persecutory delusions because as they believe that others are "out to get them," they have a strong self-preservation instinct to protect themselves, which is why they react aggressively and violently. In addition, many individuals are persuasive in trying to get other to believe their delusions, which is why you view her as manipulative. In fact she is not so much being manipulative because she actually believes what she is saying is based on facts (while manipulation is more devious in nature) and she is doing this to try to gain allies. Here is a link providing more details of this disorder for you.
We do not fully understand why Delusional Disorders present themselves, but we believe it is a part of the individual's genetics and response to certain social environments. Since your wife was not welcomed by your family 14 years when you both moved to California, she most likely felt that she was not well liked and that your family hated her. Because of her disorder, she begin to manifest false beliefs that your family was conspiring against her because of how they treated her, then those beliefs included you, and then they included friends you associated with. This delusion led your wife to further isolate herself and hate everyone else, which leads to an escalation of the disorder and the behavior that she exhibits.
Treatment for a delusional disorder usually requires intense Cognitive Behavioral Therapy (CBT) and the use of antipsychotic medication. There have been successes in treatment for delusional disorder, but it is difficult to determine the rate of success on average because some cases are very severe and other cases are mild. Also many individuals with a Delusional Disorder Persecutory Type will not trust the therapist because the individual believes they are a part of the group that is conspiring against them, so that makes success in therapy more difficult. I will say that an escalation of violence and aggression that you mentioned may warrant an involuntary hospitalization if your wife's symptoms become too severe that your safety is in jeopardy. Involuntary hospitalization is a serious step, but it will secure treatment for your wife if it comes to that.
I hope I provided you with enough information to answer your questions and concerns for your wife's behavior. If you have any other questions, concerns, or would like to discuss my response, please feel free to contact me at anytime and I will be sure to get back to you as soon as possible. Thank you and I hope I provided you with excellent service today.