Why is my ex is trying to make me jealous?

Hello,my ex girlfriend broke up with me a year ago,i did all the stupid things,like chase her and try to get her back,made things only worse,after a few months we started to have contact again,just friendly,(I still have feeling for her even now). When I was talking with other people for girls and sex she was mad at me and she was replying do whatever you want with them,just leave me alone,we had many fights in the past months and she was acting like a bitch making me annoyed at her and ignoring her/sometimes even say a bit harsh things(I know its bad). The last 2 months she ignores me completely but lately she is trying to make me jealous by flirting my friends and stuff.Tried to talk her a few times but nothing worked.She is still ignoring me and she is avoiding me,some friends told me that she is mad at me and this is a good sigh,she has feelings for me but I am not so sure...

Keep in mind that she hasn't been in a relationship this last year,i would knew it,she had sex a few times as I did as well thou!