I'm sorry you had such a bad day...I wanted to let you know that I had to do the same 360 leadership assessment and it's possible your boss could have sent invites to other people if he didn't feel your list was comprehensive enough.
Is it possible this happened? We do a similar 360 assessment during annual reviews and I almost always augment the list my employees give me.
(caveat: I didn't have time to read all the responses you got, so ignore this if someone already called this out as a possibility)