Confused and scared

Sorry this is long.

I'm kind of freaking out. In 2 1/2 weeks I'm starting with a therapist who specializes in PTSD and until now I've never dealt with any of this. In the past, my therapy was for my anorexia (which I'm recovered from...took a long time, but I got through it) and I never talked about some of the deeper issues from the traumas. I kind of smoothed over them and didn't really give the whole story. I was too embarrassed/ashamed/in denial about it. Besides the anorexia, I've been working with pdocs to get my the right combo of meds for my bipolar II, and until a year ago I was in a deep depression or hypomanic most of the time. It was rare for my mood to be steady for more than a few days at a time. So when I was in that deep depression, I didn't really feel much, and when I was hypomanic my thoughts raced so that nothing really stuck with me for very long. Anyhow, we finally got the right combo of meds a little over a year ago, and since then the PTSD symptoms have slowly gotten worse as small bits of memories have surfaced, and they aren't drowned by the depression or blocked out by the ED anymore, so the feelings actually stick with me. The past week or two as I've tried to decide what I want to talk with the new therapist about, I've kind of had an avalanche of feelings and memories and I'm very frightened. I never learned how to cope with any of this since it's always been buried beneath the anorexia and the depression. I haven't done any SI in years, but it has become tempting, and I DO NOT want to go there again. Please, does anyone have any suggestions on what to do? I don't feel equipped to handle this. I'm also nervous about starting therapy, since I figure it will be different from the ED therapy. Is he going to want me to tell him every single thing that happened right away? And there are pieces of memories that are missing, is that common? Like I remember how an incident started, and then there is a blank spot, and then I remember what happened after the incident. Does that make sense? Thanks for any help!