This is tough, and to be totally honest, I'm not sure if there is a violation of hipaa here.
Certainly your partner's boss telling everyone you and your current partner has AIDS is unethical (not to mention flat out rude), but, unless he was told this information by a doctor of yours, there's no violation. If the rumor isn't true (you didn't say if it was or wasn't, I'm assuming not), then I don't think there is a violation. Regarding your boss telling your partner's boss how your previous partner died - I think that since your boss was not your partner's doctor, there is no violation. Is your current partner's boss a medical professional?
I wish I could give you a concrete answer, but I honestly am not sure about the legality of the situation. Hopefully my response will bump your question so someone who DOES know will see it and give you an answer. In the meantime, please check out the links below for filing a complaint for a hipaa violation; perhaps they will guide you in the right direction.
http://www.hhs.gov/ocr/hipaahowto.pdf AMA (HIPAA) HIPAA Violations and Enforcement
Good luck to you, and it is such a shame this is happening to you. The people spreading this information have no ethics whatsoever.