[0] https://en.wikipedia.org/wiki/Dialectical_behavior_therapy#D... [1] https://www.bustle.com/p/what-is-mammalian-diving-response-t...
Just talk to them like you typically do to anyone, you need their money, they need you to make money.
And always remember no matter what you do, very little is going to change despite the outcome and you are almost insignificant and is playing a very tiny part in the universe. You are just doing your own thing.
In essence, making your exhale longer than your inhale will calm you down. So take 10-20 deep breaths through your nose, focus on your breathing by following it, once you're breathing comfortably after the first few, try and make your exhale longer. It's OK to count in your mind if that helps.