How do i get my ex back? I'm on my last chance.?

Me and my ex have been best friends since this time 3 years ago, when we met back in 9th grade. Last year (10-20-07) i started dating her and we had an amazing relationship. We fell in love fast and hard, and we went everywhere and did everything together. Well i started getting kind of clingy and on top of that, i'm bipolar. I love her to death and i would never hurt her on purpose, but i started getting jealous of other guys, and i didnt trust her fully. So this started causing a few fights over the summer, and into now, but i promised that i am changing,i promised several times, and i keep letting her down, and i'm not trying to. On the 10th she dumped me and removed me from her life, all contact completely. The reasons are because i keep letting her down and i haven't been giving her time to be herself, i'm clingy, and i don't trust her, and it's just negativity on her in my opinion. Now she says she'll never forget me, but i don't know if she loves me or will ever talk to me again. Like an idiot, i immediately reacted and called her phone a bunch of times, leaving pathetic messages begging to talk to her, i did this up until that sunday, and then i didnt call her all day. I broke down again at night and called her. The next morning( the 143h) I called her mom to make sure she wasnt home, and i dropped off a dozen flowers, some candy, and a nice little card saying i miss her and i love her and how sorry i am. When i went there i noticed the promise ring i got her was sitting there, and it hurt, because she always wears it =/. I stopped calling her, but only 2 days later, the 15th, i made an idiot move. I got a ride to her house and went to her, followed her around, and it ended with her in her bathroom crying and telling me to leave, and me outside the door yelling i love her and asking if she even cares and saying stupid **** like oh if it was jimmy you'd care.(This is her friend she's been hanging with, she's known him for like 5 years so they hang out alot now)I regretted that so much and called and apologized, no-one answered. I found a box of old notes she gave me saying how much she loves me and if she can't have me she wants nothing and she's there forever, etc. They made me break down in tears so i wanted her to see them and see how things were, so i put them, some candy, her favorite soda, and wrote an 8 page letter to her, stuck it all in a box, dropped it off at her doorstep, knocked, and left. Now i hadn't contacted her again, or tried, until Monday, the 20th, and i only did so because that would have been our 1 year anniversary, so i just wanted to say hi and check up, she didnt answer and i ended up calling 6 times and leaving just as many messages. Later that night i called again and just told her i love her and i miss her and im always there. I sent her some messages on myspace telling her to come to a concert with me, and another with a huge collage of our old photos, some very recent, some from a few years ago, just to commemorate our would-have-been anniversary. She didn't open the messages, it tells you, they just said sent, so i deleted them. I was hoping she opened the package, but found out earlier she didn't. My friend danny asked her if she got anything from me and she said yeah and she opened it and got the candy and stuff, but didnt read the notes, which sucks. Her friend jess who takes her to school every day told me to stop obsessing and give her space, and that she'll never forget me and told me she doesn't like anyone else and knows she won't for a VERY long time, which i agree with, because she never really liked anyone from her school except me. She also told me that when i went there i scared her, which really upsets me because i didn't mean to. I know that she is happy right now and is just being herself. I really honestly can say that i am MADLY in love with this girl. I can't take my mind off her, like people say to, i just can't. I've tried everything, games, sleepovers, going out with people, etc, none of it works. She's always there, and she's one of the most influential people in my entire life. I want her to be happy and it really really hurts that i let her down. I want to at least be her friend again, and from there we can move slowly back into a relationship, but for now i just want her to talk to me again so we can be friends again. I'm very alone and i live in a different city than her since i moved, so i don't really have friends up here. I don't have anyone i can tell things to, and i'm just lost without her. I love her to pieces but i'm really scared of her thinking i wont change and i will just be the same way, and she'll just move on and find someone else. I don't want to let her down anymore and i really have stopped contacting her this time, to give her space. I'm scared that i've messed things up too much and ruined my chances, but i can't deal with that, i love her too much and i can't get her off my mind, and quite frankly, i don't want to.