How do I cope with the emergency calls that went wrong?

You are excellent at this. You read a call in seconds and send the right help, over and over. And still, you carry the ones that did not end well, the ones that stay with you long after the shift. That weight is not a flaw in you. It is the mark of someone who never treated these as just calls. Here is what you have to hold onto. You did not cause the emergencies; you met them. In the ones that went wrong, the wrongness was almost never yours. You entered someone's worst moment and did what could be done, and sometimes what could be done was not enough. That is the tragedy of the work, not your failure in it. Carrying them means you cared, but carrying them alone can slowly crush you. Stop carrying them silently. Find the people who do this work and talk about the ones that stay, or find a counselor who understands the job. Say the hard ones out loud. You gave those callers everything you had. You are allowed to set some of the weight down.