Crazy friends

Friends are very important but what happens when one goes nuts? I had this super close friend, she said I was her adopted sister, that close. We were not a 'couple', just good friends for 16 1/2 years, then out of the blue, apparently I said something wrong, then she sends this dumb email like back in high school, telling me never to email or call again. WTF is that all about?
Also stating that she was a better friend than I... ok, now I'm really annoyed... I lent her 14k for a new car, let her stay at my house for one year rent free, and I got here a job - doesn't that count for something?? I have had some financial woes lately, she claims I used that to be on edge; well, how come everyone is allowed to be moody once in awhile but me? If she was such a great friend and I have been crossing boundaries, then shouldn't she tell me, accuse me, have an intervention, something, but noooo, she cuts me off even of facebook, good grief. I am not 17 anymore, this stuff drives me crazy!