Will I ever feel happy again?

Some days feel fine, almost normal. But inevitably the pain and sadness creep in and then I wonder if I will ever feel unconditional happiness again. My daughter just finished her first year of school. She has finished kindergarten and the teacher was kind enough to send home a book of memories collected throughout the past school year and as I look through it I see dates and seasons and I immediately link them to the affair and its aftermath. I think that is the day they started talking, they were getting really intimate with eachother at that point. I would find out a day later my life was over. I should not be looking at my daughter's experiences and accomplishments and tie every one of them to the disaster that is my marriage. I wonder how long things will work. I feel like I can't be honest with him about how I truely feel because I feel like if I doubt we will make it, he will just give up now. I want to just move on but I always come back to the fact that he slept with someone else. He gave himself to someone else. Yes, he's here now, but his response to difficulties in our marriage was to confide in someone else and eventually be intimate with her in every way imaginable. I just don't know how to get over that. I feel like I don't cry as much, but maybe I just don't see it. I haven't  been sleeping much and I feel so anxious all the time. I feel awful about myself and while I have reason to be critical of myself, it's so much worse than that. I just want this weight to be lifted, the saddness to melt away. I want to not feel anger when I look at him, I don't want everything I hear and see to remind me of his infidelity. I don't want to be the bigger person. I want an eye for an eye. I don't see his saddness and grief unless I'm really upset or angry and attacking him. It's like everything is fine for him, he doesn't think about it unless I make him. I'm having a harder time not lashing out. Today I just want to cry. I feel so hopeless and it's overwhelming. I know he loves me but it doesn't seem like enough. I want to curl up and hide until it is all over. I just don't know if I am strong enough to make it through this.