Is it normal to dump my girlfriend my having another girl call her?

so i had been blowing off my girlfriend for a while and avoiding her, but she was the stupid type and thought i would actually be loyal to her and stuff, so one night she was waiting for me to drop by her door and pick her up, but instead i was with another girl i had been seeing. i had a brilliant idea to make the girl i was with call up my girlfriend and tell her that i was busy and wouldn't be keeping in touch with her anymore. i told the girl i was with to use words like "bitch" and "slut" when talking to my girlfriend. i felt a little bad but she deserved it for being so naive. i mean she was a virgin and we had been going out for a few weeks and i still hadn't had sex with her...she was too innocent to think she had a chance with me or that i was interested. and i figured if she got a taste of cold hard reality then she would smarten up and learn that life isn't all rainbows and butterflies. the way i see it, i did her a favor.