Hey, Doreen !
I feel your pain. Some days, you can't win no matter what. Do you happen to have a pillow ? Go ahead... scream into it. Punch it. toss it around. Tell yourself it's okay to let off some steam. Go outside. take a walk. I do find a good brisk walk around the neighborhood helps too. The fresh air will certainly do you some good.
We've always been taught that the customer is always right, even when they are wrong. What to do ? Be polite and be professional. That's all you really can do. If that isn't good enough for that person, then you bump them up to your superior. There is only so much you can do and some times, a person will keep screaming until they think someone is listening to them.
It's frustrating. So, you take things one day at a time. Don't beat on yourself if you turned to food for comfort. Today, you eat a little better. You treat your body a little better. You'll start feeling a bit better.