Should i hate my bff for goin out with my ex bf?!?help nao!!!?

Ok so my ex boyfriend and i started texting again recently and i thought things were going great and that we might get the chance to get back together again,and i kePt talking about him and all until everyone got annoyed,sO i went over my friends house and i slept over and she was texting him,i didnt really care much cuz she knew how much he ment to me,but the. I read theire txts and i got jelous but i still trusted her bcause she knew that he was my first love/kiss,but a few hours ago she texted me saying not to hate her because she was going out with him,but i cried i screamed i cursed and i hated her,she was always ripping on him,and she was always saying that she would never date him but now she is! She made out with her ex boyfriend at only 2 days,now im scared of what she might do to him:( he is older then her,and in a higher grade,and a few days ago he was telling me about some girl he liked in his school, but i think that he is desperate,well he ruined my friendship with ashley,and he wrecked my heart! I was with him for 2 years! I hate her!!!! I have the right to be mad at her but i need to be put to peace anyone help me? My ex bf+ex bff=