When you act how another individual behaves with you, you may think you’ll do the same with them as well, but, on the contrary, what you’re doing is falling down to their level.
If the other individual is unkind to you, you cannot do the same to them, or else what’s even the structure of your values if you’re selective with them.
Instead, you need to maintain your level, your standards, and your values. Be how you want to be, irrespective of how others are to you. Instead of acting like the other person, act like you.