Why is my soon to be ex-husband more angry and bitter than me, he cheated?

Why is my soon to be ex-husband more angry and bitter than me, he cheated? He's still with his girlfriend and they had a kid a year after we separated. You'd think he would be happy. In my case I've moved on and I have furthered my education, and many other good things have happened to me. In fact, he did me a huge favor, by leaving. Hell, I even thanked him for leaving me. I still have feelings for him... with the memories and all, but I think that's normal. I truly hopes he learns from this lesson, for the sake of our kids. I forgave him and his gf in my heart, it was hard, but liberating.