Welcome gnossos and TealBlue to the LD4all comunity! 
gnossos, at one point everyone wonders if they are doing with their real body what they are also doing with their dream one; but in most cases, the answer is no, fiction and reality stay mostly separate 
I can’t really advice you on Lucid Nightmares though, as I’ve never had one. You can find a topic on it, though.
TealBlue, dreams can be so powerful sometimes, they can change our very essence. Glad you come to us to seek information, I’m sure you’ll find plenty, plus an affable community of users! 
Good luck to both of you 