Why do i still like him?

well i still have feelings for my ex..i find it hard for me to move on but i can't! .when we were still together he liked this girl,i did hate her but now i don't cuz he doesn't like her anymore. i asked him if he still has feelings for me and he said he does..and after i asked that i recently noticed that he IMs me less and less everyday...do think he's lyin? i wanna tell him that i like him,but i know he's gonna think i'm weird.ahh! i need some advice to forget him...