<human>: So my girlfriend has started to get weird texts and phone calls from alot of people she dosn't even know. They all said that they saw a post on 4chan from someone claiming she was a "cheating liar and needs to be punished". I know exactly who the guy is that posted it, but how do I go about getting him to stop or getting him back for that? It's just cowardly of him to use other people to bully up on her for no reason other than jealousy. Thankfully, one of the 4chan-ers from Tennessee called my girlfriend and warned us in the first place about the post, so if he sees this (I wish) I really would want to thank him.

Can you summarize the given text in a few sentences?
<bot>: My girlfriend's ex is jelly, got mad, and is using 4chan to bully us. What should we do?