My husband cheated. How do I let go of the anger?

We were married for 8 yrs. I found out after he left that the cheating had been going on for most of those years off and on. The only reason why he told me of the despicable things he had done was to piss me off further. He is a manipulator and narcissist. He even formed a closer relationship with our daughter when she was 7 in order to take me to court for shared custody. Of course, he blames me for the hurtful things he has done. I found out I was pregnant when he left. He insisted on a 50/50 visitation schedule for my daughter before we even went to court and would not let me see her on his DAYS. He is not engaged to his mistress of at least 2 years. He told me a few times that he is a happier person now and a changed person. So, he is supposedly more responsible, quit drinking and is more of a family man because of this woman. What does that make me? He has decieved me and manipulated me in such a way that I did blame myself for a while but I started to get wiser after I had the baby and took my life back. Although, I am still beating myself up for trusting him for so long, putting up with his drinking and crap, and especially staying with him until he left ME! He humiliated me in front of family and friends by making everyone think that this new woman in his life is a much better person and will be a better wife than I was. I know my ego is suffering here but how do I get over the anger and bitterness? I know they are not my concern and I feel a tremendous weight lifted since I am not with him...by worrying about his infidelity. But, now but I have to listen to my daughter also tell me how wonderful his girlfriend is. Now he wants me to meet his girlfriend to show me what a great person she is. She may be, and I hope so for the sake of my kids. He is starting to keep our 6 month old overnight every other week and is trying to get shared custody of both children in addition to a step son he will soon have to start his new family.