Although my grandmother was not a 'nut case', the way you described your wife, you could have been describing me as I treated my husband. No problems, I would invent one and rave about it.
my husband and I have divorced but he is still supportive of me and I say this; bipolar disorder was the death of our marriage.
My husband and I hung in there for 23 years.
Do some deep breathing, go for a walk, make sure you are eating a sleeping well. Life may be tough living with your wife , but it does not have to be insane for you.
Most of the time a bipolar person does not even know they are out of control. Find a psychiatrist or a psychologist to help diagnois your wife. Perhaps your city has an out patient psychiatric program. Go get help. In helping your wife you are helping yourself and your family.
Ruby