While you may not end up friends, establishing mutual respect is essential. Don't Return the Volley. One strategy is to refuse to fight. After trying reason, stop responding to inflammatory comments. Prepare to ride out the storm.
Most typhoons blow themselves out.
Responding to Threats. An owner or director suing the Board is like shooting yourself in the foot. When it comes to physical threats, waste no time. Call the police. This kind of behavior needs to be stopped cold.