My thought is that she wants a totally new life away from you and start from scratch.
You say that you've been cheating on her since practically day 1 and you've been married for 19 years. It's not hard to see why she wants to cleanse herself from you. Seriously, can you honestly predict that in a month's time or more that you won't be cheating again?
When you were carrying on your A's, how did you treat your W? Again, you have to give us specific details. Start from the beginning and how you started straying. Were you tired of her? Not wanting to be married? Don't wait for us to keep asking you questions. You have to be the one to give us specifics.
You can save this and like Zeus said, it's going to take alot of work on your part. Because of your long history of infidelity, the quicker we cut through the BS the quicker it will be to create a plan.
And READ THE BOOKS.
M-43 W-40 2D - 9 and 5
Emotion, yet peace. Ignorance, yet knowledge. Passion, yet serenity. Chaos, yet harmony. Death, yet a new life.