Dexter Did It, Again.

Hello, everyone. I regret to inform you that Dexter has once again, called me a slur. This time, god it was so bad I don't even know if I can say it on here. In the calm before the storm, I was happy, it was a normal day. I was laughing with one of my friends, let's call them Bee. Bee and I were joking around, and suddenly Bee said something hurtful about Dexter. Dexter was absolutely fuming! I could hear it in her voice. I tried to apologize of Bee's behalf, but Dexter was NOT having it. Instead of instigating an argument with Bee, Dexter started an argument with ME? I was so confused when she started throwing insults and slurs at me, and yes, slurs plural. I was hurt, and of course I tried to defend myself. She will probably come on here saying I was the one who started the argument, when I was in fact, not. I defended myself, and I, too, said some hurtful things. It was all in self-defense, so can I really be blamed for my hostility? I am so conflicted at the moment, I need some advice! What should I say when I confront Dexter about their ill advised antagonism?