I effed up my relation ship and need to fix it?

so to lay down the base of it me and my girl friend were going quite steady we had been dating for around 4 months. About a week after a date we had it was time close to finals and A.P. test. i never wanted to interfere with her school work so i stayed at bay sometimes. if id text her and she said studying or homework i wouldn't text her to avoid getting in the way. id try each day about and would get the same response and me not wanting to mess with it left well enough alone. this went on for about two months until on the last day of school she broke up with me. after three days of me banging my head against a brick wall for being such a dumb *** i decided to do something about it. i sat down at my computer and wrote a two PAGE letter this letter contained my pure heart and soul, it took me from 8 pm till 5 am to finish just making sure things were perfect. the reason i sent a letter was because it is a physical object that cant be deleted from an inbox and carries the message better. i mailed the letter and two days later she changed her status on facebook from single to its complicated. we talked for a little and she cant even finish the letter it makes her cry almost. i went to kansas city for about a week and didn't tell her so there was this lapse of contact for a week now i feel ive worsened things by not trying to meet up with her till now. so my question is how can i mend this relationship. what did i do wrong from the start. if your a girl what would you want a guy to do. generally how can i fix this mistake, i care so much about her and we have so much in common i dint want to lose her because ive my not wanting to interfere.