I like a girl that has a boyfriend.?

Alright, let me start by saying this was my last resort to post on yahoo answers to ask this question haha. Not that I have a problem with it, but I thought I could settle it myself. Well, here goes a long story: This girl is in 10th grade; I'm in 12th. I'm pretty much best friends with her brother. I met her this summer and instantly knew something was there. within 2 weeks of knowing her, I really cared for her. I didn't want anything to happen to her at all. About 3 weeks after summer ended (let's say september 10), i started talking to her on facebook a bunch. we had pretty long conversations fairly often. i could tell i was starting to like her more... and then around december 10, I thought I liked her, then on about december 18, she gave me her number on facebook and said we should text instead of talking on facebook so much. on december 22, i'm at my grand dad's house, and get on the laptop to log on and see if i had any messages from her, and it says she is in a relationship. my face felt cold and i felt really surprised and didn't really know what to do. So, i went upstairs and just laid there thinking. the next day, i get a text from her just saying hi with a frownie face, "Hey :("... so we just kinda had a normal conversation and didn't even mention anything about her boyfriend. her boyfriend has been her friend for a while and he is also in the 10th grade (yes, i got owned by a person 2 grades below me haha)... so we text for like another 5 days, and then we pretty much stop.. then about 12 days later, around january 10, she starts texting me again, a lot... and i barely know this kid, but i'm pretty sure he's a cool guy, so i always felt a little guilt texting her, even though i know it's only texting, but i obviously had making her my girlfriend on my mind in the back of my head. so she texted me literally everyday for about 2 weeks, and then she sort of slowed down. maybe 2-3 days a week, up until about February 10. Now, she has been texting me more again, but not a ton.. and she always tells me things that make me think she likes me... like she leads me on really bad... i really do think i love her, at least as much as a guy can love a girl in a relationship with a guy that is a good guy haha... and the reason i keep saying he is a good guy is because it makes me feel really guilty. I would hate it if this girl was going out with me and her actual boyfriend was texting her a lot... but she has told me she has had dreams about me and just stuff that makes me think she might like me still... haha and i forgot an important thing... on about december 21 (haha, yeah one day before they started dating), her mom said that she liked me (she told one of my other friends this, not me)... and the girl also told me 3 days ago that she was planning on asking me to sadie hawkins and hoping i would ask her to prom, i'm guessing until her boyfriend asked her out... and i guess my main question after all of this is: Should I keep trying to text her and keep fighting to get her back? or should i just sit back and accept that he got to her first, and that's it not my terrain? and by the way, i'm not trying to get them to break up in any way, shape, or form... i'm simply staying in close contact just in case something ever did happen, so then she would know i was right there.. haha, well I can't really tell how much i've typed because it is scrolled down and not on a full screen, but if it was a lot, thanks for reading :D. Honest answers, please haha:P... oh and one more thing, on facebook, she has a picture of him kissing her on the cheek, and it makes me SO mad to look at haha... just thought i would add that..