No, the ER is not the best and worst job in your life. That would be a paramedic.
Imagine seeing all the things you see, only in the unsterile, often unprotected world of Out There. Before the police get there to keep the person with the gun away. Or search for him. Before the Fire Department gets there to move that car off your victims trapped inside the mangled mess.
I have worked in both. I started in one as an aide then moved on to the other as a paramedic then returned to one as a PA-C. Both are crazy stressful and will kill you if you let them. I am glad you saw it and got out alive.