Most companies issue an employee handbook that outlines the details of work place relationships, you should start there. Your HR department is probably not a safe haven for you in this circumstance, they'll probably be neutral until a decision is made.
If you feel like you're being harassed, you could get help from a lawyer specializing in employment / workers rights. I do not recommend this -- there's a huge risk in retaining an lawyer. Your employer would probably consider you a troublemaker and they might find another reason to try and terminate you.
Personally I would just sit it out. If they find nothing, they won't have the right to take action against you. If you are terminated wrongly, that's different - then consider the lawyer.



