I have a lot of questions about my wife's conduct and if it is related to dementia or is a mental disorder.

Dementia effects people in different ways, Things that are common are short term memory loss. So asking the same question over and over is typical. Depending where it is in the brain , Dementia is known for reversing personalities. This does not happen to everyone, Someone who was normally patient became very impatient. If the person was always on time, became disoriented when it came to time. Her behavior seems to be part of the diseases normal destructive path.
I would suggest that you educate yourself on this disease and consult your Doctor. For now live in her world and remember that she must be so scared and confused. It has to be extremely frightening to be lost in your own mind.

Aggieflyer65, My Luz was DX with FTD and PPA (primary progressive aphasia)
Time meant nothing to her. Getting her dressed was a chore for both of us. Simple things became the wrong thing. She would try to consume her drinks with a fork until I would give her a spoon. She used a fork or spoon to push food onto a knife and eat from the knife. She would try to pour a cup of coffee but had difficulty realizing the cup was full, leaving at least two cups of coffee poured onto the counter. the last time she tried she forgot the cup. She developed a cough and would spit any where or place. I carried a towel to clean up the messes.
She still liked things orderly and would stop me in stores to straighten up shelves. Or she would pull stuff off of the shelf to put into our cart that she had no need for. Most cashiers understood something was wrong and would to me for an answer. She still loved people and would stop to help anyone in need.
Her aphasia was so bed she quit talking and just made a one of two noises. One for help with something and one for her confusion with a task. She could still talk but did not or it might take her five minutes to answer with one word. If sshe knew the word. She started to eat less and lost about 30 pounds. It seemed like chewing was too much work.
I mentioned my concerns to our primary and he took it as simple age related until he ask her some questions and she just laughed. His tests resulted in us being sent to the Cleveland Clinic for simple clock test and a CT scam. Her frontal lobe had shrunk almost a quarter of an inch. She lived less than three years from the date of DX until her passing.
It was a difficult life for me but I loved every minute I was with her. I did find a good source for hiring a companion to allow me to get out for a few hours to do some shopping because life still went on and we needed things.
I think each of us could write a book on the life we have had or are having with a LO and no two books would be the same.
If our lies were taught in college it could result in a new degree program up to the Doctorate level.
You are doing a miraculous job. I wish you the very best and to listen to the advice given here. Return often and and share your life with us.
God Bless you.

Has your wife been examined / assessed by a professional / a physician?
I would think this would be the first course of action once these behaviors started.
She may need to be medicated.

Also, while it would be 'good' to identify what is going on with her brain, in some ways personal to you, your behavior will need to adapt / change accordingly regardless of the diagnosis, i.e., if she's calling you 50+ times a day, regardless of the reasons she is doing that, you will need to change your response / automatic behavior.

Do you have a therapist or professional you can go to for support?
This would be important for you right now. So many families / spouses are forced into this unknown territory and have no language, skills, or knowledge to handle it. It isn't YOUR or anyone's fault. People are not equipped nor trained to handle or interact with these health issues - and when they happen, family is in a state of shock not knowing what to do. This is a good site to turn to. In addition, do google TEEPA SNOW and watch some of her webinars. She is the country's expert on the many different conditions of dementia.

Take care of yourself. This is critically important: eat healthy, meditate, exercise - do what you need to do to keep yourself together.