Friend and i fallen out over a boy. now shes being an idiot?

in september last year, i finally told my five close friends who i have had a major crush on for 3 years, i only told them because he told me he was moving away so i was upset. they told me to tell him before it was too late in case something could of happened. but i'm quite a shy girl and it took me a couple of weeks to finally tell him. so i told him, nothing happened and my 2 friends tried to set me up with him. in january this year one of those friends called me and was like having a fit down the phone telling me not to hate her and when i asked what was wrong she finally told me she was going out with the boy i liked and had been for 2 weeks behind my back. all of my friends fallen out with her and i couldn't even bear to look at her. then she started having ago at me and one of my friends saying we were bullying her brother when we didn't even know she had a brother, she started kissing him in front of me on purpose, and to make things worse she told a bunch of people that i fancied her bf and made out that i was just jealous and she was Innocent. the other day she apologized to my one of my friends and said how she wants to be friends with me again, i cba to argue anymore so i just said yes, we hugged and then she went of to lesson. i haven't spoke to her since but my friend re added her on facebook and she accepted her and when i added her she ignored me! i know it doesn't sound like a big thing to flip over but she does my head in. today she split up with him AGAIN for the fourth time. the last 3 times that happened it put my hopes up but then they got smashed when they got back together. this time im trying not to get my hopes up because i know theyl get back together. but a friend told me she said its 'just a break' and they still like eachother. when my friend asked her if we were friends on msn she blanked him for 20 minutes and went offline. then he asked her over face book and she went offline. obviously she doesn't want to be friends and tbh neither do i. what should i do about her?