You should be able to get out of this, people do all the time for a lot less important reasons. I don't think you will get to questioning phase, unless you missed a deadline for returning paperwork or something. But yeah, if you do get that far just say you have PTSD and just being in the court room is triggering for you. Believe me, they don't want to put anyone through any harm, and if you became badly triggered and couldn't finish, and they didn't have a substitute, they would have to throw out the trial. Nobody wants to do that.