How to say good-bye to an unhelpful and undisciplined professor?
My friend, I would suggest that you start by seeing a medical professional, and the dean of students in your department or university.  If it is difficult for you to describe your situation in a conversation, then write a short statement and start the conversation by giving the statement to the person.  There are multiple aspects to your situation, but I want to make sure you understand that a university has a responsibility to support its students, and the job of a medical professional is to care for patients.  If your university has an office for students with disabilities, you could talk to them as well.  I think that your level of distress is making it more difficult for you to deal with your academic stress.
Now, about your academic situation.  Your advisor is not everything you would have liked to have as an advisor.  But please try to focus on the positives about him and your relationship for now, and postpone processing the negatives until later.  Supporting your parents is your top priority right now, and you will start to feel better when you are able to begin helping them.  Wanting to care for elderly, infirm parents is a basic human drive.
Here is a proposed text for when you go see the dean of students.  If
necessary, you can have this translated to the local language.

I am
giving you a written statement about my situation because it is
difficult for me to begin a conversation about my problem.
My parents
are alone and in poor health, and I feel an urgent need to finish my
PhD and leave [name of city or country where you are] to go care for
them.
This worry is making me so distressed that life has become very
difficult for me here.
I believe that I am ready to graduate, having
completed my PhD research and published several papers about my work.
I don't know how to convince my advisor that it is time for him to
schedule my defense.
Is there someone in the university who can help
me communicate my situation to my advisor?  I am finding it
increasingly difficult to carry on ordinary conversations because of the high level of distress I feel.

This is a simplification of everything that's going on with you at present -- but that's okay.
For the medical professional, you can also list your symptoms, for example: thoughts of suicide, frequent nightmares, difficulty concentrating, difficulty smiling or talking to people -- and anything else that may be going on.
For these conversations, you must set aside the feelings of despair, while you are having the conversation.  It should be as though you were there negotiating for a friend or acquaintance, not about yourself.  Make sure that you don't get discouraged if the first person you speak with does nothing to help you -- just try someone else.
If you need to show your statement to a receptionist or secretary, that's okay.  You owe it to your parents to get the help you need.