Im in big trouble....please HELP???

Ok so I am dating this girl that I am totally head over heals in love with and the thing is she has a boyfriend. I dont really have a right to complain because I knowingly put her into this position when we first started dating four months ago when I knew she had a bf. Ok so Im a prick I know I know but I had liked her for three years prior to when she started going to the same college as me. I realize that that really doesnt give me any right to complain at all because I put myself into this position. please refrain from telling me what an idiot i am I am already well aware of that fact. Should I leave her so that I can be the bigger person and maybe miss out on the love of my life? or should I continue with this stupid predicament Im in of being "the other guy"? I am truly in love with this girl and I know what love is. Please give me some sound advice, I realize Im a bad person for puting her in this predicament and I just want to do the right thing...Im so in love with her