Alex,

I also employed EMDR in the treatment of complex PTSD. It is hard to separate what I felt with the EMDR with what I felt with remembering and mastering the memories and associated feelings. My treatment went on for years, so the theme for me is that, no matter how bad it felt at times, the EMDR generally made the feelings more managable. It was often a journey.

You haven't mentioned any background or details, but I would say that if you are trying to deal with a long term and deeply felt issue or trauma, you need to be well prepared for it. Safe places have been mentioned. It is also important to feel safe with your therapist. And if there is some disassociation, I can speak from experience. If there is a threatened part, it/he or she will make sure that you don't feel anything. The preparation for EMDR can sometimes take a long time, but without it, the EMDR just won't work.