If life was fair and easy, it would be boring as well. I have had issues with employers and employees, customers, building officials, bankers, insurance people, customers, did I mention customers, suppliers, material, partners, payments, no money...you name it and I have had to deal with it over the last 34 years.
With that said, the best rule I have learned (and it was a learning experience...) in coping with any of the above mentioned situations is to not loose my temper. Make no decisions when mad and learn that it if it is not going to affect my life in 20 years from now, it is not enough to frazzle me.