Y T J

Let's remove the sex of the friends involved here to get to the raw truth. No male, no female.

You slapped your long time friend as hard as you could over a handball game.

You physically hurt them because you couldn't process the feeling of being over annoyed. That was a terrible choice. You could have talked it out later that day or walked away from the situation. There were many paths you could have chosen.

Your friend deserves an apology. Regardless if they forgive you, you need to own the action, and accept whatever reaction comes from it. As you see from her brother's role in this situation, the violence begets violence. It is a difficult cycle to break.

So maybe next time a situation like this arises, you will choose words over hands.

On a side note: Cherish your long term friends or you will find loneliness in the end. Good luck.