How do I handle being responsible for a whole crew's safety?

You became the site foreman. Now you answer for the whole crew's output and safety instead of just running the machine you mastered. That is a big widening of the load, from being responsible for your own work to being responsible for everyone's, including whether they go home whole. Feeling the weight of that is exactly right. The safety part is the heaviest. When it was just your machine, you controlled the risk with your own hands. Now other people's choices sit on your shoulders, and you cannot be everywhere at once. That is a real and constant pressure, and it makes sense that it presses on you. It presses because you take it seriously, which is what a good foreman does. You cannot personally guarantee every outcome, so put your energy where it actually works: clear standards, honest habits, a crew that watches out for each other because you built that culture. Do that well, and you have done your real job. The rest you have to trust to the people you lead. Pick one safety habit to reinforce hard this week, then trust your crew to carry it. Responsibility does not mean control of everything. It means setting the tone and letting good people meet it.