First interview Friday, drawing a blank and freaking out

Hi, I have my first group interview this Friday and I’m a nervous wreck!! I’ve been practicing basic questions and ethical scenarios but I keep stuttering and blanking despite not even being in front of an audience. I don’t know what to do, I feel like this is about to go so poorly and I don’t want to let anyone down. I just can’t formulate coherent thoughts and idk what to do and how to mentally prepare. Does anyone have any advice on how to not completely embarrass myself in front of a group?