I wish I could say how but I have reached the scary calm stage for a while now and I'm LOVIN' it! It's a nice change from all the anger, resentment, crying and 'this can't be how my story ends' thoughts. Though they do surface from time to time, it's not as intense and consistent as it used to be. I'd say resignation/acceptance and deciding to let go helps in getting you to that stage in a way.