I cannot believe I'm having to bump this. Really, I thought we were all mature enough to get it. This included 'he said/she said" between players, as well as between players and DMs.
Toxic behaviors will get you banned. Period.
Mom has spoken, put her foot down, and counted to three.
Basically, PvP for the purpose of telling a story is fine. If in doubt, ask a DM, or ask yourself, "Would I punch a guy in the face in real life for this?"