Hope this afternoon goes well for you (I'm sure it will). Your AN is almost exactly the same size as mine, and in the CPA too. I had CK last March, and am quite glad I did. As you know, you could have some minor ups and downs after CK, both due to the tumor and due to the CK. All in all, I'm not sorry for a minute that I had CK. I reached the same conclusion you have - a tumor this size is too big to ignore (in my opinion), but still small enough to treat with radiation.
Rest (if possible, if you're on steroids), and know that this procedure can take a few days to a couple weeks to get over entirely. As we love to say here, "individual results may vary," just like individual reactions to treatments can vary.
If I had it to do over, I'd have taken more advantage of folks who offered support, and had more people stay with me during the days/nights after treatment. Some folks on this forum were fortunate enough to be able to go sightseeing, etc. after their treatments, but my reactions to the meds were not so good, so I didn't feel too well.
Take care!