I am sorry for what has happened to you. Yes, it is terrible. The more I stay on this site and read everyone's stories, the more convinced I become that marriage repair is not a do-it-yourself job.
At this time you can only give him time and space. Read Divorce Busting and Divorce Remedy. They can still help you. IF he ever changes his mind again, you should push for assistance in reconciling -- either retrouvaille or marriage counseling (or both). To just swing with the wind of one's emotions is damaging to both parties. Getting along with a partner takes discipline.