Thank you so much for posting on here. I relate a lot to what you've written. The thing that helped me deal with the overwhelming, intense emotional instincts related to certain tasks or "triggers" was something called "Schema Therapy". It involves a version of the exercise your psychologist has suggested - writing things down and rationalising them - but it also involves trying to understand where these strong emotional instincts came from, e.g. whether they actually served some important purpose in the past. Schema is widely used on psych wards where many patients have really strong, entrenched emotional patterns that are not serving them well (this is where I first encountered it.) I was very skeptical at first, but I believe it did make a difference in my case. Over time you gradually get better at catching the dangerous, spiralling thoughts and emotions, reminding yourself they're likely related to something from the past and not relevant to your current problem, and moving past them before they get out of control.
It's great you're seeing a psychologist, and they may have experience in Schema Therapy if it sounds like something that could be useful for you. There's also heaps of resources and worksheets for it online. My psychologist isn't a Schema expert (like I said it tends to be the clinical psychs working in psych wards who are most familiar with it), but we were still able to talk about the concepts together, and she was able to help guide me in using it effectively.
The other thing I have found with work anxiety is the essential importance of letting things go as much as possible, and not working yourself too hard. I found when problems arise I tend to entire "firefighting mode" and find it difficult to stop work for the day until the problems are solved. This quickly leads to spiraling anxiety and burnout. Now I'm extremely disciplined at just working an 8 hour day, and leaving any problems until tomorrow (most things are not as urgent as they may "feel", although I realise this may not be possible for all jobs!)
Take care of yourself mate, and well done again for posting on here.