Okay so i have this one friend who im no longer friends with, weve been friends for 9 yrs. Answer PLZ A.S.A.P!?

Alright well over this last year ever since 2010 started i noticed this unfamiliar change between us and we started growing apart and when we hung out i thought it was fine at first but it really just wasn't the same as it used to be. I understand friends and people change and grow apart its natural. So we were really really good friends though. We'd been friends forever. Until one day she just decided that she was moving on and we can't be friends anymore. Our friendship was always on her terms, whatever she wanted to do you know? But i stuck with it through the good and bad and i was there for her and we were a great team. We'd always send each other emails go on trips and pretty much do anything together. And her family was so great to me, they all loved me. Her mom was so generous. And to be honest at first i was pretty mad that she just left me in the dust because she transferred to a diff. school and met new friends but we still live in the same house and in the same town. Okay so here's the thing, i miss her now a lot and ive done stuff with other friends gone on vacations over my summer, kept myself busy. But i still really really miss her. And how do i know if she misses me just as much or not? I see on her facebook page she's out there being busy with lots of her friends too and im happy shes enjoying herself but i just cant do this i mean there are times where i really miss what we had. I didn't want us to leave our friendship alone. So im kind of thinking about sending her a really really short message, u know one that just says 'Hi.' Or maybe something like 'How's you're summer going?' and we're not friends anymore but i really wish we were. And she was a bit of a jerk to me but i know it was a mistake and she'll come around eventually. My dad thinks she'll get sick of hanging out with her new friends and decide one day she'll call me again. Or if u don't think the message thing was a good idea what if i send her a birthday card just something simple with a tiny message saying happy birthday or something with my senior pic inside of it because its our last yr in high school? I mean what do i do? I still want to be friends with her. Thanks!!