I have been through what you are going through. My ex had done the same thing to me but was also seeing other girls at the same time. If he did not find what he was looking for through the other women he would comr to see me. Our divorce was a mutual decision but he was the one that wanted it more I tried through the divorce process to get him to agree to work it out but he kept refuseing so I got a stronger back bone and excepted it but yet when he would come around for one thing only (sex) I would give in.
We both had a hard time letting go of the "comfort" of being with eachother for so long, so when it was time to move on and try to date other people I think it was a fear and discomfort of being with someone else.
You need to get out and make your self sociable with more people of the oppisite sex. The more you become comfortable around new people the easier it is to let go.
I spent several months out with my friends at the bars dancing and haveing a good time getting to know other people and also having dates that when my ex came begging me back I knew in my heart that we were not meant to be.
I finally met a gentleman that I am madly in love with and have spent 3 years with him. Though it was a very short time after my divorce I have found the one.
My ex and I have remained good friends for the kids sake and we are both happy with our current lives!!!!!! I hope this has helped some. Just remember to get out and get to know the new you because we all change to be a different person after a split. You become stronger and wizer.. Heather