First off.. sorry that you should have to pretend like that.
I spend enough time to prepare myself mentally .. like i do things which make feel calm,
Try to convince myself it will all fine or
I write all thoughts down,try to talk to myself, convince.
But, i think i don't look much suspicious because i am a silent person.. so, it doesn't raise a red flag if i don't talk too much, or appear like im not present there. But if you are a but active person.. i can't be of much help .