False promise of marriage by girl and cheating

My gf not refuse to marriage promise 9 month & now giving reasons she has no feeling. Actual story: She had a x bf & to get his attention she told me dt she likes me & started loving me She told me to ask at my home which I did dn talked about getting married, have children, about honeymoon etc stuff. I also asked for sex & she had no issues with it, she called me at her place when her house used to be empty. I changed myself & did all the adjustment to keep her happy also used to spend money cos she used to ask me for things After her birthday she started ignoring me, when I came to know about she is asking her x to come back & got me just to get attention of him & send our kissing pics to him i got mad and angry, I this angrer started to force her to get married which she promised or have sex which we used to. Give 100 of calls cos she ignores me. I said will tell her parents what she did if she refuses. Now she is saying to file police case on me for blackmailing & forcing her