Please Help, what would you do? Very confusing?

So i have this friend and we used to be best friends but lately she has been blaming things on me that are recking her rep and she calls all my friends b*****s and slu** and who**** and she even called me a slu* and a b***h, i am neither one of these things. She is the only one who has ever called me that and everyone tells me that i am very sweet. Well anyways this girl tries to get with every guy in my life. She dated my ex, she has a big crush on a guy i just got over and it took like 3 years to get over him, and she made out with a guy that i kinda had feelings for. I didn't have huge feelings for this guy but we kinda had a thing going. One night i was mad at him and she told me to give her his number so she could b***h him out and then after she did that she started talking to him and the same way i talk to him, it made me a little mad but i got over it. Then i found out that she was going to his house at lunch one day and apparently they made out. It was her first kiss and now apparently she has a huge crush on him. I am really mad at her for doing this to me once again. I seriously am not jealous, i don't get jealous but i am mad cause now this boy won't even talk to me. I have tried to talk to him over text but he won't answer me. I am not gonna stop talking to the girl, she just isn't gonna be one of my best friends anymore, which means she will never know any of my crushes or anything cause then all of sudden she likes them too and i am scared to date anyone cause i don't want her to date him after me. Should i be mad? Am i feeling the right emotions? Am i over reacting? What should i do? Please help! :(