It seems that at best he's royally insensitive and at worst he's rubbing he's rubbing her nose in it, while she's been left to pick up the pieces, so I can understand why she reacted.
It is childish & undignified (especially the picture) and she's probably already kicking herself for doing it without anyone else jumping on board.
I'd be amazed to find someone that can claim to have never had a mad moment in the wake of a painful break up - I know I can't.