How should I handle this catty office drama?

My female supervisor retired a few months ago. She's was quite the queen bee. She held a big retirement party at a swanky location and speeches were flowing like a river. She gives a big flourishing good bye speech and she gave specific thanks and adulation to each member of her staff. However, she "forgot" to mention the support staff (HR person, clerical person, IT person - all females.

They were pissed, and rightly so. But I don't think it was intentional. Well, hell hath no fury like a henhouse scorned!

Fast forward to this week. One of the support staff women is leaving the office to move to another state, and a going away luncheon was planned. Some of the old employees who left/retired were invited, but the former supervisor was not. The problem is that the former supervisor is still a friend to many of us, and she has now found out about the party. She called me to bitch and I think she is pissed that I am going to attend.

Here's the question, how does a working man best navigate this potential minefield. Professional lives are on the line, believe me! These ladies are starting a war.