I am so sorry that you find yourself in such a difficult situation. It's hard to imagine a family member being the one who hurts us. I can so relate to what you are going through because I have a 36 year old son who is verbally abusive and sees himself as the victim even though he is the one who is toxic. Like your son, my son lost his dad when he was young. Some circumstances are different, but the anxiety, uncertainty, and fear are the same.
No one deserves to be treated badly. I have come to realize I am a domestic violence victim, and it seems especially difficult when it's by an adult child rather than a relationship I can walk away from. Right now I am in a crisis with him, and I feel afraid and hopeless. I tried to help him, but no good deed goes unpunished.
There are wonderful, wise, and often hurting parents on this site who will give you much appreciated support.
One tip. Try to break your posts into smaller chunks, which are visually easier to digest.
Prayers and love.
