How Do I Stay Calm During My Testimony At My Sexual Assault Trial?

Basically the title. I was sexually assaulted at work last summer by one of my clients while doing an at home visit. I worked with at-risk youth, so it took law enforcement several months to find and arrest the person who did this. I had to transfer departments at my job, have been having nightmares and panic attacks daily, and have genuinely blocked most of the details out of my mind because my mental state has been so fragile since this happened.

The person who assaulted me was arrested about a week ago, and pled not guilty at the arraignment. I was just subpoenaed to testify, and genuinely don't think I can be in the same room as this person. Does anyone have any advice for staying calm on the stand? I want to be able to survive my testimony and any cross-examination so that I can actually get the justice I've been waiting for. I don't want to be too emotional or get too worked up, but I just don't know how to do that when he's going to be right there. Any advice on how to navigate this would be seriously appreciated, I'm a wreck right now.