Jealousy? guys opinions? BA?

Okay so i dumped my ex a few months ago but we are still friends... hes liked me for over 2 years and lately hes been on and off with it though. Hes tryed to make me jealous before which brings me to my question... well now he keeps bringin up this nasty slut who everyone hates? well yeah he talks about her all the time and i feel like hes trying to make me jealous he even asked if i was mad about them hanging out? well yeah is he trying to make me jealous or am i full of it? he tells me random things that he is with her and what they do together.. she has a bf but he acts like they have a thing. he just says things like that all the time. so whats your opinion? haha thanks!