The difference is simple.... she's punishing them for what they did.
It's justice. She's not targeting innocent people. She's putting them in the position they forced others in. Sure, she's enjoying it... but I feel that it's fine because it's them.
That being said... while the ex-boyfriend was probably a little annoying, it's also true that she didn't properly communicate... so that's all on her.... so I 100% agree there...