Can't say much about stalking in general.

What I can say is don't interact with strangers on the internet. FFXIV is not exempt from this rule; FC's can give you a little insight to that perspective. Everyone having played for a while will understand what I mean.

You don't randomly become a target of harassement unless there's a connection or information revelead to the person in question. I rarely hear about these issues by experience alone.

Don't share sensitive information about yourself. Create a few criterias that have to be met in order for someone to know you. Don't lower your expectations to be part of a group or fit into their clique.

As for OP, I sincerely hope they'll look into this issue. All the best to you.