There's a girl i've like for a long time who i know ..what do i do?

There's a girl who i've like for around 7 years now and when i met her i was just overtaken by her like no other, she was around 4 years older than me, which i dont mind and never considered until i met her, i like everything about her, so long story short i asked her to lunch back then we went on a few lunches and at the time i was 19 and after a couple lunches she started dodging me ..my guess cuz i seemed square at the moment ..but ive come to know know her aquaintencely since then and i would always ask her to lunch again but she said that she had a bf and no and seemed like she somewhat enjoyed giving me the cold shoulder, ..i finally asked her to lunch again one day she said yes, so i met up with her at her work she was talking to some guy outside, and i waited as she knew i was there, after a minute i said hi to her quietly interupting .. she looked at the guy like "oh great" look and we got into an arguement right there infront of the store, she said some hurtful things and i felt hurt. i ignored her for about 8months until she round about like appologized when i accidently ran into her, ..anyways i was sad cuz i couldnt stop thinking about her, ..this went on, i tried to call it a crush and forget about it, but i could'nt..,and the last couple years (2) we just seem as we're cool and over it and friends, and now i just started getting to talk to her more i seen her on myspace, and we seem really cool' so far but again she has a bf it says on her page but i've liked this girl for soo long, ive been in other relationships since then and what not but she's always on my mind .. i dont really have a specific question, just confussed. I would like to get to know her more and go on dates but thats not gonna happen at the moment cuz she has a bf.. but im also afraid what if she has a kid or something with him and never got to say what i wanted from my heart ... any advice will do.. thank you.