Please take a look at the criteria for Borderline Personality Disorder and see if it fits. If so, the good news is that it can be treated. The less good news is that such people are a bottomless well of need. No matter how much you try to support and validate your wife, it won’t be enough. Understanding how afraid she is may help you feel less frustrated with her.
Since your wife refuses to go to therapy, start with yourself. I cannot advise you on how to approach your wife about engaging in treatment as I don’t know enough about her. An in-depth discussion with a therapist may help you disengage from the roller-coaster of your wife’s accusations and identify non-threatening ways to invite her into therapy.
I wish you well.