My t and I have done EMDR and do quite abit of ego state work. Since I'm so sensitive and easily flooded, she has had to go slowly with me so i don't get overwhelmed. We made a few mistakes at first where she let me get too far into my pain, and it felt traumatizing for me. But we learned to go slower, and that works much better.

If you're afraid you might get overwhelmed with this work, maybe just remind your t (more than once if necessary) that you need to take things slowly so it doesn't emotionally flood you.