Husband had an Affair...how can I cope?

I had been with my husband for a total of almost 10 yrs but we were only married for almost 3 yrs. My husband recently had an affair. He had the affair with this women for only 1 mth b4 i found out and so i kicked him out. He has only been seeing this girl since Feb. but yet moved in with her right away. He not only left me but also our 2 yr old son. He claims that he does not love me anymore. How can he just move on with someone else like that and throw away all our history? I feel deep down that he still loves me because i see it in his eyes. I just feel that he thinks the "grass is greener" with her. How do I cope since he's been gone now for 3 months and i feel its getting harder and harder. He just recently picked up the rest of his things on our 3rd year anniversary. I just cant help but feel he's made a mistake.