Julie - My wife did the same thing. Told me she loved me but wasn't in love with me, had an affair and filed for divorce.
Let me tell you one thing - you have got to remain strong. I felt that it was impossible for me to get where I am now, but guess what, I am here and stronger than I have ever been. Growing through adversity makes us stronger and builds our character.
Sam is right about the church. I couldn't do this on my own, and never had I ever turned to God - EVER. But when I finally broke down and invited Him into my heart and soul - the next day it was like I weight was lifted off my shoulders.
Granted - you'll still have tough days, but as long as you let Him help you, you'll be fine.
A longtime friend of mine who helped me out in the beginning told me, when this first started, that one day I would feel sorry for my wife. Well, I completely understand what she meant. My wife is in bondage because of the destructive path she is leaving. She is alienating the kids, pushing me out of her life for good, and finding a temporary "fix" in her new man. Let me tell you, sex does not make a relationship and running away from yourself can only lead you down a dark path of regret.
You'll be fine - trust me - mark my words. Trust in Him and He will lead you. He is the Way, the Truth and the Life.

-Jim