Help please! advice needed on possessive girl?

I have a problem, there is this girl at my school that i like, but her friend (they aren't best friends, just friends) keeps bothering me. she has told me that she would help me with the girl i like and has since done nothing but tell her whatever it is i say. but now im trying to talk to the girl i like but i notice that her friend doesn't like it. for example, last week was our prom and she kept asking me who i asked and would get hurt when i wouldn't tell her and she told me i shouldn't go to prom, so i asked the girl i like and her friend didn't like that. I am stuck the girl that keeps bothering me already has a boyfriend and keeps telling me stuff like having dreams about kissing me, (physically)touching my hair during school and txting me about every hour on the hour asking what im doing.i don't know what to do she says she loves her boyfriend but won't let me near any girls. what do i do???Help please! advice needed on possessive girl?
Girls everywhere will really respect you if you communicate to her to back off. Just don't exude any nice-ness when she starts. Be silent, don't crack a smile. But when you're allowing her to be flirty with you like that, you're sending a message to all the girls, including the one you actually like, that basically anybody can share that relationship with you. She's taking you down and controlling you.Help please! advice needed on possessive girl?
Be straight with your gf Best tell her me or her gf otherwise it isn't going to work?