Sad day

My divorce was final on September 25, 2007, and I thought that I had dealt with it. My anniversary was on Tuesday 3/11, and my ex informd me over the weekend that he was staying with a friend last Saturday. I determined through a little investigation that it was with a new girlfriend. I am just devastated. I miss him so much. I relieved the last horrible 16 months of our marriage in one day. He turned 40, developed cataracts resulting in surgery, and turned to drinking and hanging out with 20 year old waittresses at a local "family" bar. I remember all of the mean things he said to me when he came home drunk like dancing around the kitchen in joy when he found out that I was the one with the fertility problem. And the time he told me that I would make a horrible mother. Now he is planning another getaway with her on Friday, and I am just devastated. I have been having panic attacks nearly every day, and I have never had this happen before. Yesterday, I worked up enough courage to call his mother, and she helped me a lot. How can I still feel like I belong with him? We talked around the time of the divorce as he had started to get his life straight again, and we discussed the fact that maybe we could be together somewhere down the road, but how do I get passed the fear of him finding smeone else?