Well... Yeah, I kind of figured that you couldn't drop out. As for humiliation- why don't you make a very, very public post on how she's really creeping you out?
Doing so would insure that everyone would be aware that any harmful actions on her part towards you are pure retaliation. An insurance policy, if you will.
The fact is that 'keeping up on the gossip' isn't what she's doing, she's... I dunno'... monitoring? the fandom. That's like someone hiding in the bushes and listening to people talk, not walking up and joining in the conversation.
For evidence, you could point to this convo~ I don't even know what fandom you peeps are in or who you are, but I think it's pretty skeevy.