About the stalker:
It was probably just a random troll trying to rattle you and sound like they did, at least a little.
Try this if it happens again. Click on their character, then in the chat box type "/killme". It should give you an option to submit a trouble ticket. Part of the trouble ticket process is to capture all the data around you. Don't know if Cryptic will actually do anything about it, but a least they will have a digital record. Put a footnote to Cryptic that if you don't hear from them in 72 hours that you'll upchannel the ticket to Perfect World. That behavior violates PWE's policies.