PSA: When you are punished, only YOUR actions and sayings matter, nobody else's.
It doesn't matter if someone have an abusive behavior with you in the first place, if you talk back by using offensive words or having an abusive behavior, you are considered violating the player behavior chart, thus you are toxic/punishable aswell.
The best thing to do in ANY CASE is to limit your interactions with the player (mute chat and, if they are excessives, mute pings).
Keep in mind that the punishment system will trigger only if a report is done. This goes in both ways. Make so you can't be reported for anything. Don't seek for any form of retaliation.
Seeing a lot of people complaining on the boards for getting punished because they were "trying to defend themselves", I feel like this was needed.