Is this rude of my friend to do this?

There was a guy who kept flirting with me and he's 16 and i'm 15. (so he's a grade higher than me). he usually just wanted to text me sexual things and for some reason he ignored me for like 4 weeks, then apologized, started talking and then he stopped. i decided to prank text him when my best friend was over with her phone. she's a grade lower than me. i told her not to tell him it was me that gave his number but she did anyways. now he added her on facebook and i told her not to accept but when she went home that day she did. he flirts with her now and i'm like wtf he's such a player. like he's a perv. and my BEST FRIEND was flirting back and she tells me she isn't. he texts her good morning now and everything and it's really pissing me off. i guess you could say i'm jealous but today my best friend asked me if it's ok she texts him and she'll stop if i tell her to, but i just said no it's fine because i didn't want to be rude. am i over reacting or is it rude of her? he said that he would date me at the beginning of the school year but i guess not... he changes with too many girls.