Can you help me figure out what this dream means (see details)

Okay… so I’m going to preface this by saying that a. I’m not a mean person b. I can barely kill a fly and c. I love my sister VERY much, she is my best friend.

I had a dream early this morning that I killed my sister. The dream was extremely vivid – I shot her in the head, standing just feet away from her. I can picture the image of her with the bullet in between her eyes, but there was no blood. I was very much so “in” the dream, everything was kind of hazy and I had no reason as to why I did this. I told a friend after and he said something to the effect of “you’re probably going to regret this in the morning.” The dream continued on and some of her old friends were in it, along with my parents—no one was crying or even too upset with me, but I was completely distraught and feeling great remorse, but still in a hazey state. There was more to the dream but it was all unrelated to this incident.

I woke up very upset and concerned. My sister and I are on great terms and as I mentioned, I love her with all of my heart. I have no reason to have had this dream and it kind of freaked me out. Any suggestions as to what this may mean?