Hi, My name is Philip. I am an attorney with over 16 years experience. Hopefully I can help you with your legal question.
You certainly have a case over the unpaid portion of the lease/rental agreement.
You can sue her to recover the money you are out by her not giving you notice prior to leaving.
You can sue her in small claims
court to recover this.
That is more complex...
Here is what the law in HI says about blackmail
A person commits extortion
if the person does any of the following:
(1) Obtains, or exerts control over, the property, labor, or services of another with intent to deprive another of property, labor, or services by threatening by word or conduct to:
. . .
(f) Expose a secret or publicize an asserted fact, whether true or false, tending to subject some person to hatred, contempt, or ridicule, or to impair the threatened person's credit or business repute;
(g) Reveal any information sought to be concealed by the person threatened or any other person;
So what you describe?
The law makes it clearly a crime to demand money in return for a threat to
"Expose a secret or publicize an asserted fact...threatened person's credit or business repute"
Arguably, her statement does this...
That is, what you describe, it sounds like she is telling you "do not pursue me or I will tell your command"
That is blackmail.
So I do think you have a case.
You can report this to local police and ask them to prosecute (if you have the text that would be helpful)...it may be the police will prosecute this crime
Let me know if you have more questions, happy to help if I can