I feel Insulted

I know it seems i have the same problem every day but my problem is not getting any better. It seems that i'm not the best person to come to for talks these days. My friends dont come to me anymore, instead they go to each other. I made time for these people. Even though they treat me wrong, i still went out of my way to make sure that they are okay. How come they can talk to one another, but they wont talk to me? I would listen and give the best advice i can. Its another issue that is brought to my self esteem.  I love these people, but  i have this problem of not talking to them, i let them get away. Last night one of my friends took her friends that i'm friends with bowling, this is the same person who just hangs out with the same people, and when she doesnt have any one to go to a game with or something small, she will call me and like an idiot, i say yes. This friend ditched me at basketball game, she doesnt call me anymore. She never drops by anymore, but if i were to invite someone over, she will ask me if she can come over. I dont understand and then i have to say no. I think if i were to move to another place , it would help me because me and this friend live in the same town. Sometimes if i hear shes hanging out with the same people, i will lay down in bed and not want to get up. This friend was like a sister to me, we hung out all the time in high school and now things have changed. We all have a hang out spot we go to on friday nights and i didnt go this past friday, i just couldnt see her, the last time i went, she basically was saying oh i wish this person was here over and over, do you know how bad that made me feel? If i wasnt there, she wouldnt be saying that. I think i'm being taken advantage of, my friend ship is being used. I just want all of this to stop and go away.