Intrusive thought/dream/false memory I’m having trouble letting go

This is really scary to type and I guess trigger warning.

The other night I woke up from a weird dream, went to the bathroom, and then as I was drifting back to sleep this visual popped into my head. It was of being next to a dead body, at first I couldn’t place it and then suddenly like memory all these visuals came flooding back. In the memories the body was next to me in my old bed, I woke up and tried to wake myself up thinking it was a dream but couldn’t and then for some reason instead of calling for help I hid the body in the bin. This makes absolutely no sense for me to not remember this event until now if real but I can’t shake how real it feels and how the visuals all came flashing back along with having thoughts at the time like “I can’t tell anyone about this”. I’ve been ruminating on it for the past 6 days and the more I do the more “what ifs” come back like “what if I did do this because I thought it would look like I did it” “what if I hid the body because I was worried I did something in my sleep” and vivid memories of me hauling the bag with the body out of the apartment, of looking at the bin and thinking of the body in there and feeling sorry. I looked up news articles and that scared me more because the news articles felt familiar, as if I had looked it up the first time to check if anything had been found and then when it hadn’t maybe I put it to the back of my mind and forgot.

It’s been so distressing that I nearly turned myself in but I wouldn’t know what to say. Like “I think I did this but I’m unsure if this is maybe just a weird dream or when it would have happened”. I’ve barely been able to eat or keep anything down, I threw up the first day I got the thoughts. I haven’t been able to stop crying. I told my Mum and my therapist and they all think it’s intrusive thoughts because it seems highly unlikely a thing for me to do as well as something to get away with but again I can’t shake how real they feel. Again I don’t understand why I would have done this or how this is something I could have forgotten so easily and been going on with my life happily until now. Like some kind of psychopath. I don’t really know what I’m searching for here but can intrusive thoughts feel this real? Can they be old dreams coming back and feeling real? Because this wasn’t a dream I had the night I got this flash just like a visual that then came with other memories. Or am I just an evil person with repressed memory of doing something terrible?