So, my friend C works in a high-profile video game retailer. She is a girl, and that comes with some interesting side effects. Most of the guys pretty decent dudes, but once in a while you get a dickbag. And that sucks, because it's your fucking job and you can't go anywhere. In my own personal life, I have a rule about my girlfriends' other lovers: I don't want to meet them at the store because I can't run away.
So C met a dickbag, and he started following her on Twitter.* An onslaught of posts that assumed a relationship with her far more intimate than one she has with him were what followed, and she felt that this was generally uncalled for. And then she made the mistake of saying something to him. Shit has gone downhill from there, and while I would love to document the whole thing, I wasn't really there for it.
The gist of it: He did not stop communicating with her. Even when her boyfriend relayed that it would be very good for him to stop that. Even when she blocked him. Even when her friends started getting into it with him. This is my reply to him attempting to defend himself to me.
I don't like him very much.
There are a few points you made that I would like to quickly address.
What you did was uncalled for. It was deeply creepy and a huge overreaction to a person you did not know. It clearly made her feel uncomfortable and it has had a direct and upsetting effect on her. Once that was brought to your attention, you attacked the messenger with baseless accusations of jealousy; he wasn't jealous, he was protecting someone he cares about from a person that represents a clear danger to her well-being. By continuing this conversation and harrassing her friends, you are being a dickbag. This is indefensible. This is deplorable. This makes you a horrible person and you should stop.
You can't help people understand a point of view that is clearly wrong and misinformed. What you are trying to do is feel better about a course of interactions that has left someone feel victimized and horrible. That is not what you should be doing. You should be apologizing, and then shutting up. You were a dickbag. That happens sometimes, and we all have to deal with our various occasions of dickbaggery. But the mature thing to do in those situations is not to continue harrassing people; it's to admit it and shut the fuck up.
You are trying to drag her work into your abuse, and that is unconscionable. Any workplace worth working at will take one look at your behavior and then ban you from the premises. If you acted like this to any of my employees, you would be immediately asked to leave, and never, ever come back. Because I will not let my employees feel that work is an unsafe place for them to be. I will not let my employees work in conditions that are bad for their psychological well-being. The fault is not with her. The fault is with you, and if anyone is going to be facing repercussions for it, it will be you.
*EDIT! Apparently she followed him first.