Yes. I definitely know what you're talking about, everything from the delayed anger to the imaginary arguments to cussing WW out when she's not around.
For me, a lot of it had to do with the fact that even after finding out about the affair, I was still trying to save the marriage, and as angry as I was with her, I still wanted to be able to see her as someone I could love and work things out with. It wasn't until after it was clear that that she was determined to leave and had no remorse at all for what she had done that I started to really feel the anger. All the pain and emotional anguish that I had sublimated into a last desperate drive to save the marriage was now finding expression in a horrible rage against this person who had done the unthinkable to me.
For a couple of weeks, I took it out on her, which was a mistake. I didn't make her feel any worse (or at least it didn't make her feel guilty), and it just made my life more difficult. I got myself under control and started playing nice, but I still find a lot of time each day is taken up with frustrated and angry thoughts as I continue to analyze what happened and come to an increasingly negative view of her.
I'm no therapist, but I think it's probably important that you get these feelings out, that you don't bury them or not allow yourself to express them. It's also probably best if you don't express them to your WS, at least not in the heated moment that you're feeling them.
As for how to move out of this phase, I'm going to have to defer to people who are further along than I am because I'm still in it myself. I think the first thing is to make sure that your anger doesn't pollute your interactions with people, either your WS or anyone else. As I said, I've managed to compartmentalize enough that I can have my private anger towards her, but play nice in person. This is particularly important in my situation since we are sharing custody of our daughter. I'm sure some of it will fade naturally over time. It probably helps to find other things to occupy your mind as well, getting out and doing things, being active in work and hobbies. The less time you have to dwell on things, the less you will feel angry. Whether forgiveness plays any role in this process... that's still a really tough question that I haven't figured out. If you get any insight out of this process, let me know. For now, let me just say that you're not alone.