What should I do?

Ok, so, i told my best friend i liked this guy and she said he was cute but he'd be a really good boyfriend and that i should go out with him. The seguinte dia i went over her house with my other friend Lauren. Lauren called the guy and asked him who he liked and he said Mahnoor (the back-stabber) was one of them. I was mad. REALLY mad. She said she doesn't lke him and even if she did she would never go out with him. She went out with him the very seguinte day. she lied to me. Then she told me she would break up with him if I wanted her to. I told her to and she said no. She lied again. Then she said she really did break up with him and at the football game I asked him out and he said he was going out with Mahnoor. She lied again. So I got really mad and called her a bitch. The net dia she came crawling back to me sayin that she was stupid and that she gave him up for me for real this time. Now we're friends but she always talks about him. It hurts. Im havin doubts that shes a true friend. tell me what u think^^