On one hand you said that she does not love you (she told me," she is not in love with me & that was only an attraction) and on other hand you said that she does not want to loose you that means she is interested in support that she gets from you but not marrying you. If that person is interested in marrying her then he should have married her in first time only. I’m sure She must have thought this. I don’t think only his blackmailing keep her in relationship, she might have her personal needs in continuing it. You should discuss your plan with her in detail and ask her to give you answer in fix frame of time. Do not stretch your feeling beyond that and take final decision, may be tough one.