I am more of a programmer/pen tester but I understand that anxiety. I have code that I wrote years ago that is still running without issue and it still makes me nervous.

The best thing to do is to thoroughly test, purposely break things in test, and read whatever docs you have on it. In short, prepare for the worst and hope for the best. Bad things happen and there is little that can be done to stop it except to be prepared and know what you are deploying as much as possible. Do you work alone or in a team?

It is the worst feeling in the world to deploy code(especially if I wrote it) and bugs show up in production. It still happens to me, but I have the advantage of knowing the software intimately since I wrote it. Happily, any code breakage these days is meaningless but it still sets me off. Other people's code is torture so I torture that code before using it.

You can try relaxation techniques but if it is becoming overwhelming there are med options that don't typically have heavy side-effects.

I still get surprised when what I wrote runs, so I am not sure how valuable my advice is.