I understand that you have hard time to accept all this. I don't like it either, but there is nothing questionable about the disqualification, rules are the rules.
It's just how bizzare all situation is. How he hit the lines woman without even looking there and right in her throat (and she was hurt, it's visible on the video). Do you believe that sometimes some things in life are just meant to be, you know like written, fate or whatever? So how Novak won that Wimbledon last year, what were the odds? Same here, just unbelievable how it all happened, but it did and we just need to accept it as it is. Seems like Novak is well aware that he crossed the line and this time he just payed for it. Hope this will be a lesson for him to be just a little bit more cautious in the future.