Basically when all is said and done, it all comes down to this; let go. Let go and live your life as best as you can. Take care of you and get a life and go to counseling and do what you can to live the best life that you can.
I truly believe that many times it is when we really and truly let go, that the WAS looks back. But dont do it for that reason. Do it because it is the healthy choice.
Pray that he comes back, if that's is what you want, but, live as if he's not.