This was years ago but i want to show my gratitude...how?

In middle school I was somewhat of a loner and didn't really talk to anybody who treated me right but one day I spoke to this girl or should I say she spoke to me rather, she tried to be my friend and not really being all that social I was rude and put her down ( I was so mean I'm ashamed to this day) when all she wanted was to see me smile. The next year I warmed up to people and really began to socialize and started talking to her the way I should have from the start and although I was still shy we became friends and spoke every time we saw each other in the halls. It began to get to the point where I began liking her but one dreadful day I made a (seriously stupid) mistake by cursing at her when she gave me a face with her tongue I knew she was just playing but after getting into a fist fight I was seriously pissed off I know its not an excuse but immediately I tried apologizing but she would accept it. Later we went to the same high school but no longer friends she ignored me and I wondered if I should even try, I asked some body I know for advice and they told me to send her a message on myspace, it took me a couple of years to summon the courage but I finally did it and now we are friend and I apologized for treating her the way I did for that ENTIRE year and that one day. With out her I'd be the biggest a*** hole anybody could meet but just her trying to be my friend and being so great has truely changed me its hard to explain but because of her I am now one of the nicest guys anybody can meet I swear she is like my angel, we no longer talk as often as we use to but we are still friends and I'd like to tell her how she made an impact on my life but I don't know how can any body help me? We are now in college and probably won't see her anymore after we graduate and go our seprate ways this is very important to me please help (sorry I used my phone and can't see what I wrote)