How do I handle being responsible for my team's lives?

You are holding two jobs at once: keep your people alive and keep them ready. It makes sense that you do not know how to carry both yet. Nobody carries it well at first. The fact that you feel the weight means you understand what the job actually is. Readiness and safety are not really enemies. A team that trains hard is a team that survives. Most of the time, doing right by your people is the same thing as making them ready. Where they split, you decide in the moment, with the information you have, and you live with it. That is the work. You will not always get it perfect, and perfect was never the standard. Stop trying to carry it all in your head. Talk to an NCO who has done this longer than you. Ask them one plain question about a decision that is weighing on you. Borrowing another person's experience is not weakness. It is how this knowledge has always been passed down.