Best Friend and my Ex

Ok well im only 15 so I dont have much experience with this stuff so pleeeaaassse give me advice.

Well - My ex boyfriend was talking to me through MSN the other night and he was saying he missed me, blah blah blah. & I said I missed him back. And I thought everything was fine. Like, maybe we might get back together or something. So I was mega happy. Then a couple of days later I was telling my Best Friend all this and she was like “Aww how cute” blah blah blah. Then I find out they had this big as talk and were up til 4.30am having “deep conversations” and My Ex invited her to go to a party with him AND THEN my Ex had told my BFF he didnt want to get back with me & that he liked her. & then my “so-called” BFF said she liked him back. But she has this “thing” going on with this other guy and she refuses to talk with other guys so why would she make an exception to my EX?! Grr it makes me soo angry. I know she prob didnt mean to hurt me but she did. And at the moment I dont want anything to do with either of them but I know thats not the best thing to do so I NEED HELP :( Im trying to act like everythings fine (between me & my BFF) but I cant stop thinking about how mad she makes me. And how mad my Ex makes me. I already spoke to him about it and he’s full of s* I tell you. Completely full of it..