I'm laughing at an incident in which my friend's friend was humiliated
What did your friend's friend do to be humiliate?
She has a bad habit of letting out her "exes".
Sometimes you can't help but laugh when somebody gets humiliated but you should feel bad afterwards. It is mean and hurtful to enjoy the pain of others and not regret it.
Yeah, I'm sorry and I don't intend on doing it again.
That's good that you feel bad about laughing at someone's embarrassment. Sometimes you can't help it, but it's good that you're showing some empathy.