looking for an answer.. Options

[Terror]

Ok, I'm not even sure I'm supposed to be posting in this place, I dont care if you delete this topic--but I really need some answers.

Ok, first of all, since my problem is about a girl, I figured GIRLS would be most helpful, seeing as most guys are absolutely dee-dee-dee when it comes to relationships.
Ok, so to the point.
I met my ex girlfriend in 6th grade, she moved away, I continued living there for a few years, then I met her again in 8th grade.
We started going out. I realize theres alot of people arguing that 15 year old's dont know what love is, but whatever--THAT, that was love. No f**king doubt in my mind.
I fell completely for her. Absolutely and totally devoted to this one girl.
She was perfect to me, abso-f**king-lutely perfect. A few months in, I thought it would make her happy to give her a ring for our 6th month anniversary.
So, I got a job, babysat, mowed the lawn, in short, I broke my goddamn back and managed to get around 750 dollars. I went to a jewlerers, and got her the prettiest ring I could get her with 750 dollars, then I gave it to her. I like, kinda proposed half jokingly to her, like "Danielle, would you marry me?"
But then I saw her reaction, and I was actually shocked.
So we were engaged.
I bought her a necklace sometime later, (which wasn't cheap by the way)
Months passed by filled with so much love and happiness I probaly should have died then, cause I don't think I can experience uplifting joy like that ever again.
I wrote her poems every single week. Everytime we met I kissed her on the cheek.

Sex wasn't even on my mind, cuddling was enough for me.
We were perfect.
I loved her.
She loved me.
Then I found out, the day before my birthday and a few days before our one year anniversary, that she's been cheating on my, the.WHOLE.damn.time.
She's had sex with two other guys, and was messing around with a few others.
I won't delve into all the melodramatic weeks that followed, but to say the least, my world fell apart, cried for days on end, and so on.
Now, I come here, just wanting to know, was there anything I did wrong?
I mean, If I could I'd have given the world to this girl, and I tried.
I didn't even look at a girl twice for nearly a year, she was my life.

So...yeah, thats pretty much it.
And all I want to know, if theres ANYTHING you think I could've did better, or something I did wrong.
I'm just looking for answers.

-Sorry for being so long...and thanks to anyone who helps.

Then, I found out

[x3Death.By.Knife...]

Wow, I can definately tell you that you did NOTHING wrong.
You seem like an INCREDIBLE boyfriend, I can't believe that you even bought her a 750 dollar ring or an expensive necklace. And the fact that you didn't even think of sex, and that cuddle was enough for you.. it just blew my mind.

The only thing that went wrong in your relationship.. was your girlfriend.
She didn't even know how good she had it.