VS - I just wanted to offer my support to you. I know you are stunned right now and it's ok to cry. But, around your husband, you need to put on your game face. Trust me, I've had A LOT of freak-out sessions right her on this board. You'll feel better if you vent here. We know what you are going through and how you feel. Take the positive advice.. be good to yourself..
Read as much as you can. Like Mark said, pick up Divorce Remedy. Also, check out the Marriage Builders site and Love Must be Tough by James Dobson. Other people here can recommend other books. Trust me it helps if you start to get a game plan togther. You won't feel so helpless and it will give you some sense of power.
Ok.. You mentioned that your husband says you didn't say ILY or send love notes.. That's a clue as to what has happened in your M. Start there... What was missing that he is seeking to fulfill someplace else? Sounds like you had a child-centered marriage and your H felt neglected. How can you start to make him feel important to you without overkill. Build a strategy. Try some stuff.. Monitor what brings him closer and what pushes him away.