Hi G2,
First off, be welcome. I'm sorry about your AN and that you needed to find this place, but I am glad you did.
Second, you are here at a safe place to vent, complain, and talk about your feelings. We understand in ways the Normies don't.
I am not a psychologist, let alone a doctor, but let me suggest that your feelings of anxiety and depression are probably not unusual for someone recovering from a brain tumor and surgery. I have not had anxiety attacks since I got sprung from ICU, but I have had to fight against depression. I have had what I consider a long, but relatively "easy", recovery from a 31.5 hour surgery (although one of the surgeons remembers it as 36 hours...so I am not sure about the length, I was asleep) to remove most of a large tumor. When I finally awoke after surgery and found myself in ICU with a breathing tube and told how long surgery had gone, I had a very bad time. The left side of my face was paralyzed, I had double-vision, and I was dismayed by what my family had gone through (and that got worse worse when I heard some of the stories later). When the breathing tube was removed, I had no voice and very limited ability to swallow.
But, it got better.
Years ago I was raising a son with mental illness and PTSD. My wife was clinically depressed and I had a younger son with needs of his own. That experience taught that half the battle is simply getting out of bed each day and moving forward. If you can do that, you have the opportunity to fight through a lot of difficulty. Going back to those lessons, made getting through this much easier.
Another thing that helps is being able to articulate how you feel. You say you are "frustrated, depressed, and angry" and "worried about this growing again". Sounds like a good start to me. It also sounds like a number of other people around here, including myself. While I am fortunate to be able to insanely positive at times, it is not easy, and everything does take me more time and effort to do.
In short, you are not alone. You might want to cut yourself some slack and realize that maybe you aren't so far off "AN-normal." If you are really concerned about how you feel, it might be good to see a counselor/psychologist/pastor and talk about some of these things face-to-face. A local AN or brain tumor support might be worth visiting, if one exists.
Whatever you do, don't give up! Life is very good.
-Tod