A few weeks ago, on a group chat about a night out a colleague/former colleague (I'm currently on extended leave) put a nasty comment about me to a another colleague. It seems she thought the message was directly to her and not on the group. It was deleted quickly but there long enough for me and everyone else to see.
The group went silent since. I never replied or commented either way.
YABU - tell them what a pair of bitches they are next time you see them/message them
YANBU- let them stew and act as two faced as they do to me!