In life you will find that some people are too busy for you, while they will make some time for you every once in a while, they will only fit you into their schedule when it is really convenient for them.
Not a revenge-oriented person, but really. No need to even avenge ourselves. (1) God is our avenger (2) Bitterness is poison (3) Some people just don’t deserve that place in your life. Hate and bitterness take too much energy that could be put.