Same here. I've been out for what now? 11-12 years and I still get nightmares.
I guess it is our subconscious helping us understanding our feelings about what happened to us.
I would not call them nightmares but more like bad dreams, the fact that I am trapped. I want to cme back home but I cant because I dont have money or not enough time. There is all kind of scenarios in my dream but they all have thi similarity. Being trapped and not being able to get away for different reasons.
If you read Steven Hassan book 'combatting cult mind control' often people developed anxiety and/or depression after they leave a cult. I have GAD which is generalized anxiety disorder and mild depression and am very sensitive to stress now. But it took me 10 years to accept it and to accept my limits now. I will never be like I was but I am ok with who I am now. And what my limits are.
Anyway, I think many of us here do get nightmares. It is a common trait between ex $scientologists. So you are not alone.