Finding the strength to deal with death

Hello everyone!
I am in need of some serious advice from professionals who have treated patients who ultimately passed under your care. I am not a licensed nurse; however, I will be starting RN school this upcoming fall. Until school starts, I have obtained a second part-time job working as a caregiver at an assisted living facility. In addition to working at the assisted living facility, I have been working as a patient sitter at a local hospital and recently finished an volunteer-internship at that same hospital in which I spent 12 months and over 300 hours on a medical surgical floor assisting the CNAs and nurses provide basic hygiene and assist with ADLs with all sorts of patients. However, my role as a caregiver in the assisted living facility is the first time in which an individuals care has been put in my hands. Although I am always stressed having to juggle providing assistance with ADLs for numerous dependent residents, the work is extremely rewarding when I get to see the residents smile and hear their gratitude for the help that I provide. Since I will be starting nursing school soon, I often have thoughts of "am I able to do this?" I am an extremely hard worker with integrity and honesty that I hold above all things, even if it means I'm going to be chewed out or possibly get fired. I love learning about the human body and learning about its pathophysiology and the interventions that nurses take in order to halt the progression of a disease or to simply provide comfort to a dying patient. From being an intern, a patient sitter and now a caregiver, I am extremely comfortable interacting with patients and their families and would like to think that I have good critical thinking skills when it comes to knowing whats best for the patient. With all of that said, I have yet to deal with someone dying under my care. That is, until today at work. I was working with my normal list of residents: some completely dependent on my assistance with ADLs, others who are completely dependent and require only a simple safety check now and then. While making my rounds this morning, I went to check on all of my residents and thankfully, all of them were in bed and safe. I proceeded to assist a couple residents with showers, oral hygiene, getting dressed, etc. Before taking my last resident down to the dining hall, I went to check again on a particular resident who enjoyed sleeping in. This particular resident is completely independent and has never called for assistance the six weeks I have worked at the facility. This resident has a routine that they follow everyday and does not like being disturbed often. When I went to check on this resident one last time before breakfast, I opened the door and noticed they were not in their bed and no bathroom light was on which made me worried. I stepped into the room and found the resident lying face down on the floor with a large abrasion to their forehead. The resident was unresponsive to numerous attempts of my nudging and calling their name. I turned the resident onto their back to attempt CPR after I checked for both a radial and carotid pulse and could not find one. Paramedics were immediately called and arrived within minutes, but could not perform CPR due to a DNR. First responders called the time of death and I felt sick to my stomach. I had thoughts of what I could have done differently and my mind started playing tricks on me with thoughts of " were they really in bed when I checked an 1.5 hour ago or did i just see something? Should I have walked all the way into their room instead of just peeking my head in? should I have checked on them sooner?" My supervisors, the first responders, and even the family could tell I was distraught and that I have nothing to feel guilty about. I know that I did my job well today at that the residents death was tragic and nothing more than an accident or the will of God, but I can't stop thinking of what I could have done differently or if this was in any way my fault. I know that death is going to be very commonplace in my future profession, but this is extremely hard to deal with right now. I want to acknowledge this loss, pray to God to give the family strength and peace, but then I want to move on and not let this be something that consumes me and makes me doubt if I am capable of becoming a registered nurse. How have you all dealt with death? Did you start second guessing yourself and thinking "what could I have done differently? Is this my fault?". I am naturally an emotional and anxious guy, but I am also a hard worker who wants nothing more than to have a career in which I can instill joy in patient's lives for the time that I care for them. Any feedback would be greatly appreciated.