Simple solution to this question, taking it literally as it is stated. First, try telling her you are infected with Hepatitis C and other vampires have told you it gives your blood a bitter taste and see if that discourages her. If that does not work, do not invite her into your place and she cannot get you. Hopefully, she will get bored soon and head elsewhere looking for easier pickings and you could stalk and destroy her after dawn.
Okay, I guess I should have read all previous responses first. It appears that Symbeline beat me to the invitation part of my answer.
However, your question does seem to beg the question from me of, ‘How old are you?’ You do realize that since they are mythological creatures, you can make up what ever ‘legend’ you want to solve the problem, as stated, don’t you?