Maybe try to stay with it, accept it. Know that you're safe in bed, in your own home, and nothing can hurt you. Try to tell yourself that it's from the past, it's over, it's gone, there's only a memory (or a dream) that's like an echo. I agree with your T that you shouldn't pressure yourself to remember it, but try. Just don't beat yourself up if you can't remember. The fact that this is recurring means that your unconscious is grappling with something and trying to communicate it to you.

Try to put yourself in the frame of mind that you will let it happen, you will accept it. I think we can convince ourselves like this and open our minds. Maybe if you try to put this thought in your head, one of these times it happens you actually WILL remember it.

And keep that notepad handy! Good luck to you. This sounds unpleasant as all get-out.