Please do not look at yourself as a failure. You are doing everything possible to save your marriage. Unfortunately, your spouse is broken and the only way that she sees "feeling better" is filing for the divorce. MLCers are broken at a very early age by being emotionally stunted by someone in authority. It could have been her father, mother, relative, teacher, etc., but she wasn't recognized for her accomplishments or listened to by the authority figure. Some MLCers have been abused mentally, emotionally and/or physically at a young age. If she was not able to navigate each quarter life crisis, they will eventually end up having a midlife crisis.
DB is not just to help you save your marriage, but it's a way of life to help you navigate the bends, bumps and holes in your life's path. Now, pick yourself up, dust yourself off and continue being the best Gordie that you can be. Just because she's gone to a lawyer, that doesn't mean it's the end of your story. Anything can happen along the way. She could drag the divorce out for a long period of time. For instance, My xh filed and then proceeded to drag it out for two years and when I stopped the bantering back and forth between the lawyers, he then pressed forward.
The bottom line is this, if you have faith and hope, you can get through anything. The past is gone, the future is the here and now and no one knows what the future holds. Live life to the fullest and let's hope and pray that she'll come to here senses soon.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.
