Hi Saar,
Thanks for your comment. I hope you've had better dreams since this one; I know how disconcerting it can be when a vivid nightmare like that seems to come out of nowhere. While I am not a licensed therapist and cannot offer an "official" analysis of your dream, I'll do my best to offer some (hopefully) helpful insights!
In my unprofessional but honest opinion, it seems likely to me that your dream has to do with your memories around self-harm and, I would guess, your feelings about that. I won't pretend to know why your dream included the specific imagery it did--if you're worried about that, and especially if you're having recurring, distressing dreams, I would suggest talking to a therapist or counselor with experience in analyzing dreams. But given that this dream seemed to occur not long after your friend reminded you of your past, I think it's pretty safe to say that the two are connected, and that your nightmare may simply be your brain's way of working through the distress that those memories may have caused you.
I hope that helps! If you have more questions, concerns, etc., feel free to reply here or comment on future posts. Take care!
Sincerely,
Kim