Agree with most of what has already been said. I personlly would ignore the first love BS line. That is irrelevant and frankyly immature. Let it run it's course. Step out of the way. Yes, it hurts like hell, but the more you act to stop it or the longer it will go on.
The DB process is indeed for you. Follow it. It will give you your self confidence back, your self esteem back and give you clearer insight into YOU which is who you will live with the rest of your life. Even if your marriage does not work out, it will be her loss. You will come out this horrible time a better person, an improved man, the better option.
Seriously, step back, give it time, work on yourself and let her do what she wants. You can't stop it even if you wanted to. And besides, why you do want to control another person? Bottom line, you can't. They have to make their own choices, own their own mistakes, etc...
Be the man God intended you to be, the wonderful, strong man who can weather adversity with integrity. You can do this.
Start today. Keep posting. Ignore the BS. Protect yourself.