A girl is threatening me

I am 34 yr old married man working in Public sector bank. A year ago I met a girl in my bank. She was looking for some help regarding her bank a/c. As I suggest her to complete formalities in proper way so that bank can help her regarding her a/c operation. She asked my personal phone number which I hesitated to share but due to my colleague insistence I gave her my personal number. After few days she called me over my mobile to talk about her bank a/c status & so our formal chats started. About 2 weeks later I realised that she likes me. But I was not sure about that and really not wanted to be in any misunderstandings but I also enjoying the attention from that Young lady. So in general talk I told her about my married life but still she continues to talking to me. One day I asked her to meet outside my office which she agreed. I went to her house but we met outside for about 5-10 min. And that day I confessed her that I like her. She didn't replied that day. That night I realized that I am in some guilt so I called her next morning that I like you but as I am married so it’s not right to be in any relationship with her so I apologized. But she said that she is OK with my marriage and no problem with that and she knows some of her married friends who are in extra marital relationship and she want to be with me. Now we started meeting outside and talking over phone at night. During this we had physical relation and some night outs too. After some time I realized she is trying to dominate me, like demanding to meet her at my office time, talking over phone at night and for night outs. I helped her by money few time and I asked her that I cannot give you so much time but I'll try to manage but she get more aggressive by the time. Two month ago I was in hospital for my wife’s operation when she called me asking for 12,000/- rs for her exam fees. I said that at this stage I am unable to help her with money as I need it now for my wife's medical treatment but I can try to manage after few days . She explodes, and starts saying that I used her for sexual need and whenever she need help I refused to do favors. And after that she started threatening me that she wants to break up with me after telling all about me and her to my wife. I tried to convince her not to do so but she sticked to her statement. Finally I decided to spy her. I asked one of my friends to call her and try to build friendship with her so that I can know her real intention besides this entire situation. Soon my friend succeeded to convince her, without meeting her face and only by chatting over phone for sexual date. I was not surprised by that but still unknown by the real fact. So I approached her by using another phone number & being a fake Identity and she agreed here for sexual date for a sum of money. Then I decided to talk to her and I asked her that to clear her real intention as I know that she is not emotionally attached to me as I spied her. She reacted on this & started crying & said that I betrayed her and she will kill herself and will put allegation on me. I said that I spied her just to defend myself not to blackmail her, if she do anything against me I have proof that I never Kept her in deception, never hide my marital status, I have chats where she accepted that I never committed her for marriage & this all happened by mutual will. After this she started to convince me to get back to our relationship & when I denied doing so she started to abuse me over phone, text messages and “whatsapp” chat. Now I am confused what to do. It's been a months since I talked to her but still she text me everyday abuse & threaten me. I am clueless how to get rid of it. Do you think she can take any legal action against me? I know there is my fault but I never hide anything to her.