Firstly, as someone whose anxiety manifests in panic attacks I just want to give you a big virtual hug. They are just so awful and I hope you're not too zonked from it now.
I am sure your psychologist will be able to work through some things with you but I will share some of what has worked for me. Remember though, we are all different though so you will need to find what is best for you.
In addition to working through some of the 'why' of my anxiety with a psychologist, I also needed to deal with some more practical things to help cope during a panic attack and prevent future ones. To do this, I had to learn a bit about the physiological side of anxiety and panic attacks (through info from my psych and my own reading).
Firstly, ground zero, during a panic attack. If someone tells me to "take deep breaths" I'll tell them to take a long walk off a short pier. This makes me worse! However, there is a reason why there are so many old movies showing someone breathing into a paper bag. When we hyperventilate, our oxygen/other stuff mix gets out of balance, making us feel dizzy etc. So by rebreathing our own air for 5-10 breathes we restore this and absorb more or some specific something (sorry, long time ago I read about this). You don't need a bag, cup your hands over your mouth and take 5-10 breaths. Other things that help me are sudden colt temperature (go outside, stand at the open fridge, cold face washer, etc), touching another person's skin or calling someone (so I know I am real/not dreaming) and banging on a table or such (uses up pumping adrenalin).
Once I got used to knowing when a panic attack was coming, I could usually use one of these things to prevent it at the last minute.
The bigger thing has been to make big attitude and lifestyle changes to reduce my "baseline stress". This includes saying no to things, not trying to be superwoman and allowing myself to be lazy at times. When your baseline stress is high, it doesn't take much to tip over into panic levels. It also means that during unavoidable times of stress, like moving house, a work deadline or, yay, dealing with cancer, I know I need to back off even further on all the other stuff and be alert that I'm at panic attack risk/have supports in place.
I think what you're feeling is completely normal. I have "the breast cancer you would want to get if you had to have breast cancer" and I can't see myself not freaking out for quite some time yet. I can't even imagine how hard it must be for you. Don't ever feel guilty for how you are feeling or reacting, we are only human!
I do have one phrase though that I like to share. When my friend told it to me, as it worked for them, I looked at them like they thought I was stupid. It just felt too simple. She said, when you find yourself starting to worry (or despair, or stress, etc) about something ask yourself, "is me worrying (or despairing, or stressing, etc) about this actually going to change the outcome?". Then, as the answer is always "no", you can let the worry go. Just allow it to leave.
Not as in shove the feelings down and ignore them. Just observe them, understand that your feelings are valid, but don't hold them close and let them rule.
I'm working really (REALLY!!!) hard at practising what I preach at the moment. None of this is easy, but hopefully things can get a little bit easier for you.
