You'll do this one just exactly like you should do any job. You go in and you give these people x number of hours of your time, in exchange for x amount of money.
You do what you have agreed to do, what they have asked you to do, to the best of your abilities. You do not seek, nor do you expect to receive warm fuzzies from these people, emotional reassurance, or even borderline niceness. It is all about what they need and expect out of employees to make their business a success. They did not go into business so that they could give you a good and fulfilling work experience. They are not required to give you positive feedback, follow their own policies fairly, or even to treat you civilly.
As long as you are not physically assaulted, asked to work in unsafe conditions, or unpaid for hours you have worked, you continue to do your best. Do not take it personally when they try to demand that you do something that is unreasonable or beyond your capabilities.
No one can cause you stress without your consent. Do not allow them to create stress for you. How you do that is to keep yourself apart, do not over involve your emotions in the day to day what is going on with your job. If they wish to fire you because you cannot do what is asked of you, that is their call. Don't let them bully you.
I once worked in a quite stressful job situation, stressful atmosphere deliberately created by upper management which was trying to thin the ranks, with a former P.O.W. He was so calm, so peaceful, such a rock for the rest of us. He said, "I've been where important things were very bad. Frankly, this isn't important, this isn't bad." When the boss yelled, he smiled. Good luck to you.