Unmarried man having a child from a divorced women

Hi this is Irfan here I am a unmarried or single man and today my question is that I was having an affair with a divorced women and I told her that before we start our relation we will not marry each other and she agreed and she said that she has no problem being with me in live in relationship, everything was so far so good but after a year she said that she wants to marry me and I told her that this is not possible.. so I ended up our relationship and now after a year again she called me and said that she has given birth to our baby and she cheated on me because every time when she slept with me she said that she is taking pills but actually she was not, so now she is blackmailing me that if I don't marry her now she will file an F.I.R. against me and she will come to my house and she will create scene So do I really have to marry her and accept that child? If I don't marry her what complaint she can lodge? What are the legal charges she can file against me? How to get out of this situation I really don't know please give me an idea because I really have no clue!!!