Punkin, Brooklyn and Antonia are right, and it both is and it isn't a piece of paper. It ends our relationship formally, and it isn't what we wanted.
A month or so on you will feel almost certainly feel better.
You know your h isn't right in his heart and mind and soul. If he were, and it was really the marriage, he would not be with the woman he is with, and his kids and grandkids would understand, at least to some extent.
That they try and make us feel bad for their inadequacies is an index of what is wrong with them. He walked out on you because he wasn't man enough to face his demons. And may never be. But now he cannot blame you. However in MLC land things take a long time to sink in. Who in their right mind would ditch treasures like Antonia, and Mila, and Brooklyn and all those other great people who post here [by naming these three I am excluding no-one btw!].
You will feel better and here is a hug. (((((((( )))))))