Hello again, Lynx:
Uhhhh, what I said last time.
Couple more things. Your problem isn’t any longer with the downstairs tenant. It's with your landlord. I would NOT speak to her at all.
Next. Proof, schmoof! She doesn't need proof for the landlord; the landlord doesn't need proof for the lawyer, and the lawyer doesn’t need proof to threaten you. PROOF is for the judge. That's the only place you need to prove anything.
Speaking of proof. You're worried about losing? Why? DOES she live there? If she does, then you SHOULD be worried about losing. But, if she doesn't, then she HAS rent and utility receipts from where she DOES live. That's the only PROOF you need. That's the only proof the judge is looking for. Without it, you're toast.
No, you should not sue for harassment. Yes, you're feeling harassed, but that doesn't mean someone is harassing you. There IS a legitimate question here. No? Plus, if you go to small claims court, there ARE no legal fees.