Hi, she sounds a bit self-centred to me, am I right?? And it's not the number of friends (although is she really a friend??) you have that matter so much it's how much the people who are your friends really care about you, are really there for you that matters.
Now she doesn't seem to be giving you the respect, value or support that you deserve, in fact it seems like she might be making things even harder for you and you can't really want that, can you?
You say you've been through everything with her, but just how much actual, real help was she, really? And if you've been through everything with her surely she should be treating you better than this right now??!!
Still, as for you feeling worthless, at least you know that there are a lot of people on here who don't believe that you are, don't you? It might be hard for you to believe yourself, but you really, really aren't!!
Try to keep on telling yourself, making yourself believe that, please. And let this girl know that you are worth so much more than her "friendship".
Alison