Does this make her a bitchy backstabber?

Okay so my 'friend' was telling me that i should tell Weston (the guy i like) that i like him. I didn't want to but she persuaded me to so i did. then he told me that she dumped her boyfriend for him!! She couldn't have just told me? Plus, she said, "Oh Cami, you have to tell him while he's still single cause he won't be for long and you know it," and now they're together 'officially, thirty minutes ago." So she knew that I liked him and she went for him anyways? plus her boyfriend was like in love with her...so is she a bitchy backstabber?