My "friends" don't invite me anywhere and it seems like they talk about me behind my back..?

Okay so summer vacation just started and next year i'm going into seventh grade.. I have 3 close friends ( Jessica, Jocelyn, and Raylene) and they all have been to each others houses, the mall, the park, etc.. with each other and and Jocelyn has only been to my house once and Jessica about 3 times and i've been to Jessica's once. . And theres also a problem with Jocelyn; me Jessica, and Raylene are sort of in a problem with her because she's changing too much and seems to have been manipulated by the more promiscuous/backstabbing other friends we have. . She used to be really nice and kind, quiet and respectful and really overall a genuine person, but over all this time she has sort of become promiscuous, rude, and loud. Jessica and I decided to talk to her about how she has been acting and why she is being that way and we really want the real her back. We don't want to lose her as a friend because we love her and we're really close. but now it seems that Jocelyn & Jessica are doing things without me. Yesterday Jessica was supposed to come to my house and we were gonna hang out and talk this all through, but she told me she had to go to her cousin's graduation. Later in the day she posted on her status that she was at the mall with Jocelyn. If she didn't want to come and had made other plans why didn't she tell me instead of lying? Now they are best friends and are leaving me out of everything. They don't text me anymore, or invite me to places or include me in their plans. Raylene has stayed true but i thought we were all 4 best friends. Jessica and I were talking about Jocelyn and how sad it was for us and how much she's changed, but all of a sudden their best friends like nothing's happened. It's summer already and i'm afraid that i'm going to lose them because of this. They're going to go everywhere without me, and i already feel so lonely and sad. What do I do? I don't want to seem pushy. Is this a problem with me? Am i being too needy and paranoid? Please help me, i don't know what to do : /