How do youh kno if a boy is usin youh?

k so i met tis cute boy when he was already in a relationship wit tis other girl nd he told meh tat he couldnt talk 2 meh tat much cause his gf would get mad so i didnt. then later on i checked his myspace top 4riends nd his gf wasnt the 1st 1 so i IMd him bout it nd asked if it was cause of meh nd he said tat they just broke up cause it didnt work out. then a couple days later, i talked 2 him again nd he kept flirtin wit meh nd he said tat he liked meh nd i told him tat i did 2 cause i did. then he asked meh out nd i rejected him cause i wasnt ready nd he said it was ok. then we kept flirtin nd a couple days later, he told meh tat hed gotten back wit his gf so he couldnt talk 2 meh again nd i got upset cause i really liked him. nd i made it clear tat i was mad at him nd 1 day i got so upset tat i just broke down nd started yellin at him cause i felt like he didnt even like meh in the 1st place. so i told him tat if he wasnt goin 2 ever talk 2 meh again then he should just delete meh off his 4riends list. nd he told meh tat he wouldnt do tat cause tatd b stupid. so later on tat week, he started talkin 2 meh more. nd then after tat, i found out tat they broke up again nd he started flirtin wit meh again nd sayin stuff like "i miss youh" nd "ur so cute" nd stuff like tat. i just feel like im bein used cause he only comes 2 meh after his gf dumps him. nd i dont mean usin meh 4 like or anythin cause he doesnt ask meh 4 anythin at all. nd we rnt datin either buht i feel like im just a 2nd choice 4 him...idk IS he usin me?