A Girl is threatening to take legal action (Cheating) against me and harassing me If I don't talk to

Hello Sir/Mam, I just want to let you know about my situation that a Girl (whom I know from 2.5 years) is threatening me to take a legal action against me for Cheating just for harassing me. We were on good terms for almost 6 months in the beginning but two years ago, I have already cleared this thing to her that I do not want to have any future with her and she should move on. She did not listen, I try to say the same to her a number of times but we stayed as good and normal friends. I agree we had physical relationship (but not completely) after the fight but it was not under any pretext of marriage and I clearly states that we should part our ways (multiple times). In the meantime, I was with another girl with whom I was set to settle but she finds out. Although I never cheated her or was at any time in relationship with her but she still says me that I have cheated. I have apologized so many times and she even had said a lot of bad things to me any my family, but now she is harassing me that If I do not do what she says, she will take a legal action against me. Can anyone please guide me.