A few points here.
If you're at a U.S. med school, it is unlikely you will be weeded out. It is of course possible, but the graduation rate is extremely high. You may or may not be near the top of your class depending on how smart you are and how hard you work, but few people really get weeded out. If you are going to be one of these people, you will probably find this out quickly if you start failing lots of exams.
Everybody in medicine, no matter their specialty, will have patients die under their care at some point. Sometimes the cause will be totally out of your control and other times you will doubt yourself. This is not just with patient deaths, either. It's just the way medicine works. Ultimately these doubts serve as learning experiences. Learn your **** and be careful, but don't get sucked into a Hamlet-esque nihilism where you can't function because you're terrified of screwing up. While you're learning, you're supervised closely and informed of your mistakes so that you don't make many as an independent clinician. Even with all of this, mistakes will happen. Only in medicine do people have this fantasy of professionals batting 100% all the time. You just have to do your best and always try to do better. This is as good as you can do and it's no different than any other pursuit.
If you can't get over a fear of possibly hurting somebody, you are for sure in the wrong business.