I feel so much for you with you having gone through receiving the upsetting news of the tumor, that highly triggering experience with anesthetic and being left to face the seizures. That's a heck of a lot to be managing. I hope you've got a solid circle of people to help you manage (specialists included).
I can relate to the anesthetic experience. Just thinking about it changes my breathing pattern. Being a gal who's highly sensitive to her thoughts, over time I've come to distract myself from thinking about it. Takes time to achieve this. While it's a memory, established many years ago, it's still occasionally triggered. I understand what I'm about to relay may be something you'll feel, so apologies ahead of the following: With my experience, they administered the paralysing agent too early, before finally putting me under. I could feel myself suddenly not being able to take a breath in and nothing compares to the sheer terror of that feeling. You can't breath and you can't tell anyone you can't breath because you can't speak. I had nightmares for a couple of weeks following. One of them involved finding myself on another planet somewhere where there was no oxygen. I'd wake up some nights gasping for air and crying. Since that incident, I've faced a few basic operations and the main way I've managed my fear was by establishing constructive conversations with the anesthesiologists who've help me, by talking me through what they're going to do, convincing me it's impossible for that incident to be repeated. They 100% make sure it doesn't happen.They've been absolutely brilliant, including giving me a mild sedative to help me manage my anxiety.
I've heard it said that our body doesn't know the difference between reality and a memory. In other words, if a memory is triggered, the body will feel the memory as if the incident is currently happening. Again, it knows no difference. So, to repeat over and over 'This is a memory, this is a memory, this is not real' can convince the brain and body of the current reality it's in. Easier said than done, that's for sure. Developing a set of mantras for breathing is something I also found helpful. 'Breathe' is one of my repeated mantras when the anesthetic incident memory is triggered. Strategic breathing also helps regulate the nervous system.
As I say, time has distanced me from that incident so I can understand how you'd still be intensely impacted by such a recent experience. My heart goes out to you.