Threatening to suicide.

There is a girl in my office with whom I've spoke for 15 days hoping we can get along together, after speaking for those days I came to know she is not my type & we have no future together, after some days she came & proposed me to which I denied gently, now she is threatening me of committing suicide if I don't marry her, moreover she has said several times that she wants to ruin my name in society, I'm in dilemma and not knowing what to do & how to proceed further, whenever she threatens I would calm her down for that moment & convince her not to do so, now this is really taking a tall on me as I'm unable to handle this torture from her, Now a days Even I'm thinking of committing suicide(even though I know it is wrong) to escape this torture. She has her elder sisters who doesn't care about her anymore, she lives alone in a house & 3 days a week she threatens to committing suicide, I'm really worried what to do ? I can't speak about this to anyone & I don't know how to proceed further.