Not to make light of it, but I've had dreams of pets, old bosses, my second grade classroom. Old girlfriends too. People and places that meant something to us, that we felt connected with, will show up in the mind whether we're sleeping or awake.
Do you think it has to do with unfinished business?
Before I saw this I said this out loud. Unfinished business. Our dreams I believe our our way of working things out.
I think you are probably still processing it. It was a trauma. Hopefully if you try to forget and move on it will fade in time. I imagine that the fact that she is married and having a baby hasn't helped. As if she is normal and what you experienced was somehow you. IT WASNT! I think this is all normal unfortunately what you are experiencing.
I wish you all the best. It sucks I know but what I try to do as hard as it is, is try to picture what I want my life to be and move towards making that happen.