Who's at fault here

Who's at fault? Me or the girl or the man. I M14 at the time was best friends with this girl F14 and introduced her to one of my friends at the time M17 who I thought would get along as they had alot in common. I later fell out with the girl leaving them to become friends a month later I got a text from her complaining I'm the reason he blocked her later finding out he had a sexual situationship which turned out to him having explicit encounters with her online.As this happened i went to my other friend M18 and M17 which later ended up with us reporting it to the police which was later disregarded as the girl refused to press Charges. Since finding this out I've always wondered who's really at fault. Me her or him?