Welcome to the site.
I am sorry to learn about your predicament and empathise with you greatly since no parent should have to deal with the emotional coldness of her son the way you have to endure the same all these years.
It is quite apparent that your son must have held personal grudge against you for reasons best known to him and those for you to speculate.
I would like to ask you that do you feel his personality traits have been very similar to his father's ?
I shall get back to you once you reply to this question.