Yeah, when the dust settles and you start realizing it isn't just a bad dream that will eventually end, the anger moves in.
For me, the sadness and confusion lifted and I was left with rage. I had been angry since day 1, but it was mixed with so much. Then I buried it trying to find out why, learn about affairs, discover more truths, etc. As these questions stopped burning a hole in my brain (I still had them, but they weren't so crazy-making) the anger I had seemed to be the last man standing, and I had to deal with it. My fWH had to deal with it.
I don't have any advice for dealing with it. You just have to go thru it, like every other stage. You learn to hold your tongue, because if you let out every angry thought you had, you'd do nothing but spray hatred all over your WS for months.
I was told by a therapist that anger is a secondary emotion - that it's a mask to protect you. Afraid? Get angry so you don't feel fear. Embarrassed? Get angry so you don't feel ashamed. Sad? Get angry so you don't wallow in misery. You get the idea. Trying to decipher what you're covering up helps. It won't stop the anger, but it will help you see what is driving it and you can focus on that.