We're newlyweds and he cheated already.?

My husband and I have been married 4 years I am 25 and he is 27. I thought we had a perfect marriage until our 2 year anniversary, I was using his laptop to do my homework and an IM popped up saying "i miss your di*k" I was shocked and began to investigate and I found out that he had pictures of this woman. He also had been going on dates with her and having sex with her in the same house we lived in. Needless to say I packed my bags and came back stateside (he was in the army so we were in Japan). He had been having sex with her the entire time I was in America and once I moved to Japan with him he stopped. When I came home I met up with a mutual friend of ours who told me that the night before our wedding he had sex with his ex and she showed me proof. I also found out that he had been cheating on me pretty much our entire relationship. He was my first everything and it hurts like heck. We agreed to separate after the affair for 6mths and said we would work on ourselves but before the 6mths was up he sent me a text threatening to divorce me if we didn't get back together, and because I meant my marriage vows I didn't want to divorce so I told him we could get back together. But I hate him I hate his voice, his touch, and we have not had sex all year (my choice) and although I agreed to make it work I find myself depressed and wanting to leave FOR GOOD. And what makes it worst is that while we were separated because of his cheating he had a girlfriend meaning while we were supposed to be working on making us better he was still doing him. Am I wrong for wanting a divorce? And how do I tell him I want one?