When is a good time to ditch a friend?

Ok, I am 19 years old. I’ve had this friend.. Shes a yr older than me. We met in Choir. We had to be partners so we hit it off immidiately. I was a Junior @ the tyme, && she was a Senior. Were both graduated now. But weve been thru a lot together. But even all that, I’ve always felt that the friendship meant more to me than it did to her. She has other friends, but one tyme when they were fighting, && her friends were still tlkin to me, ( we had went to the Mall together. ) She kept callin me && asking about them. && always wanting to hang out. But once they all started tlkin again, she only came around every once && a while. Then another time, her internet went down, && she knew I had internet, && she would come over like everyday, but we spent a big portion of the time on the com. Using the net. She would like check her a social site && a social site && stuff. && then after like she did we would tlk er do sumthin for like a half hr, && she would go home. She always makes plans for us to hang out, but once sumthing better comes along, she will call && say she cant. && because of this, she would wanna hang out, && I would blow her off. But the other day she wanted to, so I finally decided to just hang w/ her. BUT, my day was swamped w/ crap to do. I totally didnt mean for it to happen. I was gone all day. She acted like she understood but she was acting really funny about it. So I asked her to hang out the next day so she wouldnt think I blew her off, she said yes, that she would be here @ 5, come 7 30, she txted me sayin she didnt feel good, && didnt wanna come over. I cant help but to think that she blew me off on purpose because her feelings were hurt. Then she deleted me from her a social site, ( a social site is super important to her, its like her life, only reason why im so concerened ) so I asked her, && she blew that off too. Sayin not to worry about it, && I sent her a friend request trying to blow it off too, && she was on && never added me. So.. Shes on my a social site, so I tried tlkin to her about it on there, && she gave me a REALLY BIG attitude. && was like wht the H*ll are you trying to get @ Gina? && stuff. So, I like tried to nicely tell her that I thought she did it on purpose && that we needed to tlk. It suprised me, because shes a really sweet girl.. But she like changed all of a sudden. Shes always tellim me she loves me && sayin im her only good friend, but the more I look @ it, we are not that close. Wht do I do??