We often dream about the things that we fear the most, the things that could hurt us the most. I think that dreaming that your T would betray you actually indicates that you're forming a good, trusting bond with them, because that's why the betrayal would be so horrific and why you would fear it so much.

I agree that a dream can be traumatizing. As a child I once dreamed that my mother had died, I was not the same for days afterward and I still remember it vividly. The dreams mentioned here sound absolutely awful, I would imagine it would take time to process them and let them fade.