I don't know if this will be much help, but for the most part I stopped having nightmares when I started studying lucid dreaming. Each night as I started to fall asleep I would tell myself "I will remember it's just a dream" over and over again. Eventually I did start to realize that I'm dreaming. I still have bad, vivid dreams, but they rarely frighten me because at some point during them I realize that none of it is really happening at the time.
I started doing this well before I ever entered therapy.