Have your self-respect
Lack of self-respect leads to self-abasement. All peoples’ problems are due to the lack of it. From the beginning put yourself in the right zone, and let others know about it. For example, there must be a solid reason to call oneself at late. That’s called an etiquette. If another one cannot handle it then do not interact with him and don’t waste your time on explaining it why. Simply reasonable. Have a respect for yourself and for your time. There is nothing more important, than a strict legit justified actions, that are needless to explain.
It is essential to have a self-respect. A unit cannot be accepted by the group if it has poor values. Learn to self-respect at first, then proceed to interactions. Otherwise, you will end up used by everybody and wasted. Life is not worth being miserable and spent for nothing.
Have your own respect. Let them know whom they are dealing with from the start.