screwed up bad

throwaway post. I was working in the ED when I had an admitted patient who apparently went into a fib with steadily increasing rate for 2 hours prior to shift change. I was informed weeks later not even of the situation, I was just stopped by the manager who briefly told me the situation and asked me if the monitor tech ever reported the rhythm to me, to which I said no. she said that’s what I thought and left, but I felt really anxious so I met with her after I shift and asked her what was going on. she told me that weeks prior I had a patient who declined and had a rapid 1 hour post shift, to which they discovered the rhythm change at 0500. the patient ended up being discharged but was promptly upgraded to ICU. 2 whole hours, in and out of the room and I never saw afib?? I was shocked and told her I don’t remember much of that night but I know that I check on my patients and I am racking my brain trying to figure out how that could be true, but the evidence is on the monitor. I feel ashamed of myself and I don’t know what the outcome will be. I’ve been a nurse for 1 year and 6 months and have never been “spoken to” by management nor been involved in such an awful miss. I asked her what I should be expecting and that I wanted to anything I could to ensure nothing like this happens again, and she vaguely told me that she still has a few days to work on the “investigation”. my heart simply sank and I don’t know what to expect or how to feel okay going into my upcoming shifts with this pit in my stomach.