I dealt with the dreams too... I know it is a hard thing to deal with because in a sense it feels outside your control. Several of mine were recurring and pretty disturbing.
Eventually I stopped having any dreams with the OW in them. I don't know for sure what caused the change, but I can think of three things I did differently in an effort to sleep better.
#1: Changed sleeping aid. Was taking an over the counter thing with same same active ingredient as Benedryl, started taking Melatonin instead.
#2: Started doing a nightly meditation where I wish myself and my H both peace, happiness, and compassion. I don't just *think* it, I really try to FEEL it. Like I can send out that positive energy to ask a greater power to lend us both the strength to heal our pain. If you are a prayerful sort, then that probably works much the same way.
#3: Really tried to let the OW fall out of my mind completely. She is/was a symptom of a bigger issue. There is nothing special about her that deserves my interest or examination. If my H had a boil on his ass, would I want to scrutinize and analyze it? Or would it be more useful to understand the causes of it and hope in the future I could help him exercise habits and behaviors that would prevent it from happening again? I know in your case it is a little different because you are farther along in your journey... but you really have to work to detach from the care about the OW. OW is nothing, don't give her your energy.
Before you go to bed, think about journaling positive thoughts and goals about yourself and your future. Simply setting the tone before you go to sleep can help steer your dreams ina more positive direction.
And as your Counselor said, don't put too much stock in the dreams anyways. They really are the different parts of your brain processing through memories, ideas, feelings, and emotional issues as a means of coping... but most of the time the dream itself is going to be nonsense to your waking mind.
me-35 WAS-37 T-16 1/2 Son-14 (HF Aspergers) BD,ILYBINILWY,"I met my soulmate": Oct5,2013 "Letting go because I love him, holding on because I love him."