Im angry and depressed over having inconsiderate friends

Ok basically, people are cruel. My two best friends always hang out together and make it extremely obvious, posting stuff in their away messages and stuff like that, and posting pictures at baseball games on their myspaces, and they never bother to invite me. And it's not just them, I barely get invited anywhere and one time my friend invited me somewhere and then took it back because she didnt have enough room at her beach house. And she was talking about who she was bringing to warped tour with her mom right in front of me in the car and didnt invite me? Also, I just feel like people hate me in general. My exboyfriend recently started talking to me telling me he hates how we dont talk and he wnts to hang out more and be friends and so after like a week we hung out and now he doesnt talk to me anymore, and when he does its with short answers because im the one to start the conversation. I'm so angry about this, it happens on a regular basis. What can I do without sounding like a baby. Also, im like a normal person, I talk to people and im fun and im nice, I think im a really good friend and I cant understand whats wrong with me. I have no social anxiety disorders or stuff like that!

first of all.. these aren't friends! If they were they wouldn't treat you this way. I say its time for a friend upgrade