What should i do about my friend>?

okay so my best friend was in a relationship for 2 years and her and her ex boyfriend broke up about 2 months ago and she was so in love with him and couldnt get over him and at the time of this break up i started talking to this guy that i have known for a few years and we started getting close and we would flirt but little did i know my friend was gonna stab me in the back i told her i really liked him and wanted to be with him and so one night she had called me and told me how she was still so in love with her ex and the very next morning she asked out the guy i liked so that she could make her ex jealous and he said i guess we can give it a shot and now there dating but it really upsets me that she would do that to me and shes only using the guy that i have such strong feelings for she not only hurt me but shes using her new boyfriend "my crush" and now every time i hangout with her she makes sure she talked about the guy i like and she trys to get me jealous so i need to know if i should just let the whole situation go or not be friends were her since she is so fake and untrustworthy (by the way i still talk to the guy )