Don't overthink the situation. After you've confronted someone about their behavior and things haven't improved, you need to draw a line to accept that you've done as much as you possibly could to improve relations with them. There's no more thought that you need to give to the situation. Don't overanalyze your behavior or theirs, your history of interactions, etc. Move on with your life and restore your sanity by banishing this rude person from your thoughts. Someone who is so hurtful towards you does not deserve any more of your energy.