"I'm really having a hard time grasping how my W can be so engrossed in the things that happened in the past. "
You think or believe things that you WANT to think or believe in. If all she does is concentrate on the bad stuff, it will make it seem like EVERYTHING was bad. That's why you remove yourself so that she doesn't "trigger" on just the bad.
If you are friends with her on FB, how about starting to post things of your own? Show your GAL in pictures and "Like" those comments that stress the importance of a strong M, etc. But also use it to show you're ready to move on without her. Show her a life that's different than what she has in her head.
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.