Why is my friend being offended?

we had a conversation last night about thi guy. i told her i was mad how he like competly dropped me for her. i laughed and everything. she said that wasnt true and i told her it was because there was a whole side to the story she didnt know. and she told me to tell her. so i told her how like after he met her he stopped calling me and how after she rejected him as a boyfriend he tried to approach me which i told her how that made me mad. then she was like why are you blameing me and i told her i wasnt.i really wanted to tell her how bad that makes me feel when guys do that to me and thats happens alot. i told her that. and she said the way that your putting it is like your pointing the finger at me. which i dont see how that is because i never said anything was her fault i just told her what she didnt know. so why is she getting offended? i dont know if dhes mad at me but in case she is how do i fix it?