I always believe that when people are ready for a drastic change, nothing will stop them.
It took me a long time to realize that who my son's dad was on a day to day basis is the person he is. I'd challenge you to think that you knew him. This IS him. Sad I know but I came to that realization with my son's dad and it hurt. But it was also freeing.
I had to grieve the loss of the dream though, the family, the ideal spouse. The things I NEVER had. I still had to grieve them.
There is nothing that says if people divorce that they can't reconnect or even remarry. Maybe you are putting some type of magical power on the filing process when its just papers that are stamped at the court house
I think when you get the point of letting go of the dream then you will be ready to file.
He was never that person. I'm sorry to say that but this IS who he is. And he is making you miserable. You deserve to be happy.