How do I handle the responsibility of building AI that changes everything?

You have real power now. What you build reshapes what companies do and how people work, and you can feel the weight of that. Most people never have to reckon with their own reach like this. The fact that it unsettles you is a good sign, not a bad one. Power without unease is dangerous. The engineers worth trusting are the ones who lie awake a little about the risk. You cannot control everything your work becomes, but you can control the care you put in, the lines you refuse to cross, and the honesty you bring to what it can and cannot do. Decide your own limits before someone asks you to cross them. Write down what you will not build, and why. When the pressure comes, you will not be deciding in the heat of it. You will already know where you stand.