My ex boyfriend going out with my bff's sister to make me jealous??

Well I had a boyfriend and we went out for 2 days and then he all of a sudden he broke up with me. He said that someone had paid him 30 bucks to go out with me for 2 days. Then he apologizes and says that he is sorry and that he wants me back. Well of course I ignored him when he said all of that. Then he doesnt say any of it again cause of course I told him I didnt trust him anymore. Then my best friends sister starts talking to him on myspace. Well then after they start talking he asks her to be his girlfriend and everything and she says yes. Then while I was on the phone with my best friend her sister walks in talking to him and she tells him that I am on the phone with her sister. then he asks to talk to me so they put him on speaker phone and he says hi to me but he couldnt really hear me. so he calls me 3 times nonstop until I finally pick up and then asks how I feel about him and my bff’s sister going out and I said it sounded awesome but he sounded shocked. then another day the same thing happens and he tells my bff’s sister to tell me that he said hi and he acts soo excited to talk to me even though he is going out with my bff’s sister. then he tells my bff and her sister that he’s trying to make me jealous with all of this but he says he doesnt want me back. so what the point of making me jealous. so what should I DOOO? Cause this is driving me BANANAS!