Why? do i love her so much

Hi,

I wanna know why do I still love my ex girl friend she flirts with other people in my face she does stupid an grimmey stuff in my face an I just take it. We still have sex an we still are very close some time's I think she be lieing to me but I'm not sure I do everythiing for this girl I buy her what ever she want's an I do what ever she want's.And when I told her Imma cut her off from having sex with me she gonna say never will you ever an then she gonna say you alway's gonna give it up an you gonna give it up how I want it.I'm just confussed I still love this girl but I don't know what to do with her I like somebody else but if she see me talking to them she's gonna go crazy an I don't want her to make a scene an make a big thing out of nothing dead serious i just dont know what to do any more can anybody help me ?