Hi Fresia...

Good luck! I hope it goes well, and they bring you on permanently. I'm not sure how to remain calm during the review, I have problems with that too. Maybe.... try thinking about some of the things that have happened and prepare for how you'll react if they bring them up (i.e. non-defensively acknowledge). I find that this can help me in times of stress, because I don't have to try to figure out how to react, I've already planned it a bit... it might be as simple as saying something like, "I appreciate the feedback, and am working to not let that happen again".

Can you do any visualizations beforehand? Like imagine yourself in a safe, calm place, and focus on your breathing? Do you think something like that might help calm you down a bit?

Can you think a little about the things that have happened (that you worry might affect the review) and maybe try to get a bigger perspective. Like, they may seem catastrophic to you, but in reality, to your boss, might not be that horrible. For example, if you left work for a heart attack (!!!), I wouldn't hold that against you (if I were your boss). That's clearly not your fault or something you planned!

Can you arrange to call up a friend after to "debrief" and vent and get support? Or come back here and post, and let us know how it goes!?

I'll keep you in my thoughts! I hope it goes better than expected, and you come back and let us know! Good luck!