You can try and do things in small steps. Talking about upsetting things, and working through them before dealing with the big T (trauma). Or if you're talking about the trauma, you could focus on what small aspect of it, and see how that goes. This way you can teach yourself that sharing helps, that your T is supportive and safe, and that you CAN do this. I would suggest giving yourself enough time during the session to talk about it, feel the feelings, and have your T be able to help you through them, to calm down afterward, and to have a check in/safety planning time with your T for how you will be afterward. Sometimes I finally get up the nerve to talk about something not until near the end of the session, and that makes it a bit more difficult.

Other options to make it easier: Could you write someting down to give it to your t? Bring something in for your hands to do, like a fidget toy/rock or something special that reminds you of someone, something safe? Sometimes I find if I can stay grounded while I'm talking I don't feel like it's happening all over again. You could ask your T to do some breathing or other grounding activities before you talk, and have her help remind you to breathe while it is happening.

Just some ideas to make it easier to talk. it is an amazing feeling after you fiind that courage to talk about it, and to finally feel in control of it. All the best!
xoxo
IJ