Giving up?

Have you ever felt like giving up? Running as fast as you can away from a situation or a person? Feeling lost, and incomplete? I feel as if a piece of me is out there somewhere in this world, but its not in my view or possession.
I have loved this guy for over 6 years, and I finally feel like i dont belong. I have dated him off and on, watched from the sidelines being his "friend" as he dated other girls. Now, I want nothing more then to be with him, and he is dating someone else. But he wants to still "have fun" with me. I feel like im this girl thats good enough for him behind closed doors, but she is there for the public view. I never imagined i could hurt this much from one guy. Its like he knows exactly what to say to keep me holding on, but also knows exactly what strings to pull to break my heart.
So here is the question. Do I just give up? Do i say good-bye and push him out of my life? or do i stand by and be his friend, knowing that it tears me apart?

Im sick of crying myself to sleep, im sick of feeling this emptiness in my soul. am i a masacistic person, standing by just to make sure i feel the pain?

Its like i am lost in this world and i cant find the door to my freedom. I know one guy cant solve my problems of lonliness, but he could be there for me. I cant tell him everything, because i feel like i would be a burden. Do my feelings come second when they would ruin a friendship?
questions that wont get answered tonight, so another night ill cry myself to sleep .