Bet
In the slang dictionary, the word ‘bet’ actually means something like ‘great’ or ‘word’ so this person actually was not being insulting. They were just confirming what this person said when they rejected the notion of seeing each other again. Except things took a spin when clearly this girl named Carmen could not take it.
She felt that this boy had rejected her back which was too much of a shot at her own ego. So in response, she felt defensive and had to start a fight, even though she did not know what ‘bet’ really meant. Next time Carmen, do not take everything so seriously.