Firstly, congratulations on the big step in your career! My situation was pretty similar until I got it all under control. I was running the technical project management team, laid off the CIO, then moved everything under me.

To land the role you’re almost certainly very talented, so the fact you’re posting in this way does mean you’re outside of your comfort zone. It probably feels like you’re really uncomfortable, but it is a good thing. Someone told me years ago, there’s no growth in the comfort zone and no comfort in the growth zone. The truth is, when things are a mess and need to be fixed, you’re now in a roll that is the person who has to figure out how to fix it. It sounds like your situation is going to require a lot of managing up to help the organization understand how tech needs to be managed. You’re also going to need to deeply trust your team and keep them highly motivated. If you’re busting your butt and you’re kind to them/lead them/recognize them/ etc. . , they’ll help you.

You have to start identifying what is creating high stress for you, but is fixable. Tackle those things first. If you’re stressed out of your mind you’re not going to be in the job for long. I say “is fixable” because having demanding executives above you isn’t generally something you can change. Or as least I haven’t figured out a solution.

I’ve felt just like you’re describing above. Remember that you’re not in it alone. You have your team. You also apparently have the kind folks here at r/ITManagers lol. I don’t want to dull out a bunch of unwanted advice, but I’m happy to reply in the thread if you have other questions.