My ex still wants to have sex with me and knows I have a bf!?

My ex & I have been really close 4 about 8 months. After we broke up, i would ignore him & say hi 2 his friends in front of his face. When he finally said something about it, evethough we both had some1 else, he still wanted us 2 see each other cuz he said i was always a girl he had strong feelings 4 & wanted me 2 "see" him (sex) until & even after his girl was ready (who sed after 6 months). He said i didnt have 2 do it, & i didnt. One day, my bf & I bumped in2 him @ the corner store&he sed he was so close 2 gettin him "flipped". About a month after that, he sed he was single again&wanted 2 see me cuz he never got over me. The thing is, i still do have some feelings 4 him, but i know wen we was 2gether, he wud mess around w/ other girls & i think he even had another gf cuz of the comments i saw on their myspaces. My bf treats me gr8 (except 4 $ issues cuz i usu. have 2 pay 4 everything) but im not in2 him as i was in my ex. My ex knows i have a bf but says i shouldnt break up w/ him