help? i need advice

so right now i'm confused.


see i had this friend, since 4th grade, through the winter of 9th. she was my frickin' best friend, like we were intensely close, for a long time we were everything for each other, we were close for a really long time and went through a ton of s hit as friends and kept fixing things and staying friends. and we went to different schools for 9th, and january i guess, she figured out she wasn't happy with her group of friends and wanted to find where she fit in- that's all good and well, and she was hella busy with play and such - but she shut out all but one girl of her 8th grade class, all but one of the nine of us who were a part of her class- and our class is till hella close, like we still hang, and the school went to bound us, forever, our childhood is at that school, together. she shut out all except my other best friend, whose now the person i'm closest to now. but i know that she did hang out with others at the last minute on days she told me me she was busy, like she'd be like no i have plans a week in advance and the other girl i'd talk to later, and would be like , yea, she called me that morning to hang out, and i wanted to invite you were you free? and stuff like that. it was bad. and she shut me out.

i battled depression, because the change of seasons lack of vitamin D does bad bad things to me as does personal experiences in Winter- what can i say i'm summer born.
but if it was just that she w as trying to figure out the whole school thing, and she'd told me that, it'd be a bit different. but the thing is she knew, the entire time, she was the only person that knew for a long time that i was hurting so so so bad, and in such a bad place. but i called her, she called back 5 weeks later, apologising, she shut me out, and we've talked since, and she said it was deliberate. she was passive aggressive.
and she knew she was the only one i told, and she was the first person in the world i told that i'd been molested from the ages of 6-9, and all she said was 'shit' and then preceded to bitch me out for being rude to her in the past week.

then stuff happened for her, and she couldn't talk. we didn't talk all summer. i gave up, and decided to move on, i was angry.

at first i denied what was happening, then i was angry, then accepted and ready to move on. now i'm nostalgic, i miss w hat we had, and i know that i don't get her out of my life completely and stop talking to her, i'll never know i'm strong enough to get past how bad she hurt me.

what i can't get over, is that she knew the entire time and she still did what did, and didn't tell me what was going on, just shut me out- we could be friends again i guess, but i know she won't be there, and i'll need next semester, i'll need all i can. i won't ever trust her again- i can't. i won't ever forgive her i don't think. i needed her, and she wasn't there. she chose not to be. that's what hurts the most.

i also don't want to be her second best anymore. i need to move on, so i can heal.
i know t hat being able to talk to her will only last till winter starts or she gets busy- and i don't want to hurt myself by not being able to set limits.

however, we talk occasionally, like it used to be, knowing we still have to talk, though it's dragged on weeks now.

but i know i need to let go, and resolve, and get on. i need to forgive her to move on, i need to tell her my side.

however, this is just so hard, i don't know how. i lost my nerve.

help?
how do i handle this?