Best friend drama :(?

me and my best friend had been close for about 3 years..we told each other everything went everywhere together and we got on amazingly well. about 6 months ago she started to go out with this guy. before this, she had never been in a real proper relationship. This guy is really sweet chatty and friendly , and I can see how she likes him so much. About a month into there relationship, she bluntly asked me did i like her boyfriend as it appeared that way to her and to others. I was shocked as I didnr have any attraction towards him whatsoever. She told me she didn't care if I like him or not and that she thought it was cute that i appeared to have a little crush on her boyfriend, despite the fact I actually didnt. We forgot about this and never spoke of it again. Then, last month, I noticed she had been acting quite strange around me all of a sudden. I took no notice as I thought it mite ahve had to do with her and her boyfriend, so I said id stay out of it. Suddenly one day after school i got a message saying to stay away from her and to never speak to her again because i was a lousy friend, untrustworthy and that it was evident i wanted to steal her boyfriend. I was completely heartbroken and upset as I genuinely didnt like her boyfriend in that way at all. She told me how it was obvious i was flirting with him all the time and that i wanted him to dump her for me. This has been eating me up inside for the last month as we havent spoken at all and it hurts me deeply. I have tried to apologise to her and reassure her that I dont want to steal her boyfriend...also, i havent spoken to her boyfriend at all since. What can i do to win back her friendship, as i am deeply depressed about this... :(