Sorry to hear what you're going through, some thoughts (IMHO)
1) On the one hand, nobody has the right to dictate where you can or can't be outside of official policy. Speaking strictly about where they're at, yes- annoying, but they technically have the right to loiter anywhere just as much as you do. Policy only dictates that you can't obstruct play, which is about blocking NPCs/story progress/interactables such as summoning bells. It does not generally include cases like this.
That said, your case is compelling: continue to take photos/keep evidence as you might have a case for stalking/annoyance behavior, ESPECIALLY if you DID find a new spot and they followed- document/take pictures to prove they are doing it maliciously.
2) On the other hand, saying the things they are is entirely actionable and hugely inappropriate. Report away and get them gone!
3) As others have said, I would include that link w/ the awful language in your initial post (and note it includes NSFW language). It will help people from 1/2 reading and just assuming you are acting entitled about "your spot".