Stella, dont you dare say that you are a failure. Your h has failed. He failed to tell you he was unhappy, he failed to keep his marriage vows, he failed to try with everything he had.
You stood for a very long time. There are no guarantees with db. Different things work for different people and other things dont work for some. There is no way to know.
The important thing about dbing is that we grow. And you have grown so much.
Hold your head high that you tried as hard as you could. Take care of you, be there for your daughter and remember what a wonderful person you are!